A checkmark in a mathematical formula. Designation of other unknowns

Mathematical notation(“language of mathematics”) is a complex graphic notation system used to present abstract mathematical ideas and judgments in a human-readable form. It constitutes (in its complexity and diversity) a significant proportion of non-speech sign systems used by humanity. This article describes the generally accepted international notation system, although various cultures of the past had their own, and some of them even have limited use to this day.

Note that mathematical notation, as a rule, is used in conjunction with the written form of some natural language.

In addition to fundamental and applied mathematics, mathematical notations are widely used in physics, as well as (to a limited extent) in engineering, computer science, economics, and indeed in all areas of human activity where mathematical models are used. The differences between the proper mathematical and applied style of notation will be discussed throughout the text.

Encyclopedic YouTube

    1 / 5

    ✪ Sign / in mathematics

    ✪ Mathematics 3rd grade. Table of digits of multi-digit numbers

    ✪ Sets in mathematics

    ✪ Mathematics 19. Mathematical fun - Shishkina school

    Subtitles

    Hello! This video is not about mathematics, but rather about etymology and semiotics. But I'm sure you'll like it. Go! Are you aware that the search for solutions to cubic equations in general form took mathematicians several centuries? This is partly why? Because there were no clear symbols for clear thoughts, maybe it’s our time. There are so many symbols that you can get confused. But you and I can’t be fooled, let’s figure it out. This is the capital inverted letter A. This is actually an English letter, listed first in the words "all" and "any". In Russian, this symbol, depending on the context, can be read like this: for anyone, everyone, everyone, everything and so on. We will call such a hieroglyph a universal quantifier. And here is another quantifier, but already existence. The English letter e is reflected in Paint from left to right, thereby hinting at the overseas verb “exist”, in our way we will read: there is, there is, there is, and in other similar ways. An exclamation mark to such an existential quantifier will add uniqueness. If this is clear, let's move on. You probably came across indefinite integrals in the eleventh grade, I would like to remind you that this is not just some kind of antiderivative, but the totality of all the antiderivatives of the integrand. So don't forget about C - the constant of integration. By the way, the integral icon itself is just an elongated letter s, an echo of the Latin word sum. This is precisely the geometric meaning of a definite integral: finding the area of ​​a figure under a graph by summing infinitesimal quantities. As for me, this is the most romantic activity in mathematical analysis. But school geometry is most useful because it teaches logical rigor. By the first year you should have a clear understanding of what a consequence is, what equivalence is. Well, you can’t get confused about necessity and sufficiency, you know? Let's even try to dig a little deeper. If you decide to take up higher mathematics, then I can imagine how bad your personal life is, but that is why you will probably agree to take on a small exercise. There are three points, each with a left and a right side, which you need to connect with one of the three drawn symbols. Please hit pause, try it for yourself, and then listen to what I have to say. If x=-2, then |x|=2, but from left to right you can construct the phrase this way. In the second paragraph, absolutely the same thing is written on the left and right sides. And the third point can be commented on as follows: every rectangle is a parallelogram, but not every parallelogram is a rectangle. Yes, I know that you are no longer little, but still my applause for those who completed this exercise. Well, okay, that's enough, let's remember numerical sets. Natural numbers are used when counting: 1, 2, 3, 4 and so on. In nature, -1 apple does not exist, but, by the way, integers allow us to talk about such things. The letter ℤ screams to us about the important role of zero; the set of rational numbers is denoted by the letter ℚ, and this is no coincidence. In English, the word "quotient" means "attitude". By the way, if somewhere in Brooklyn an African-American comes up to you and says: “Keep it real!”, you can be sure that this is a mathematician, an admirer of real numbers. Well, you should read something about complex numbers, it will be more useful. We will now make a rollback, return to the first grade of the most ordinary Greek school. In short, let's remember the ancient alphabet. The first letter is alpha, then betta, this hook is gamma, then delta, followed by epsilon and so on, until the last letter omega. You can be sure that the Greeks also have capital letters, but we won’t talk about sad things now. We are better about fun - about limits. But there are no mysteries here; it is immediately clear from which word the mathematical symbol appeared. Well, therefore, we can move on to the final part of the video. Please try to recite the definition of the limit of a number sequence that is now written in front of you. Click pause quickly and think, and may you have the happiness of a one-year-old child who recognizes the word “mother.” If for any epsilon greater than zero there is a positive integer N such that for all numbers of the numerical sequence greater than N, the inequality |xₙ-a|<Ɛ (эпсилон), то тогда предел числовой последовательности xₙ , при n, стремящемся к бесконечности, равен числу a. Такие вот дела, ребята. Не беда, если вам не удалось прочесть это определение, главное в свое время его понять. Напоследок отмечу: множество тех, кто посмотрел этот ролик, но до сих пор не подписан на канал, не является пустым. Это меня очень печалит, так что во время финальной музыки покажу, как это исправить. Ну а остальным желаю мыслить критически, заниматься математикой! Счастливо! [Музыка / аплодиминнты]

General information

The system evolved, like natural languages, historically (see the history of mathematical notations), and is organized like the writing of natural languages, borrowing from there also many symbols (primarily from the Latin and Greek alphabets). Symbols, as in ordinary writing, are depicted with contrasting lines on a uniform background (black on white paper, light on a dark board, contrasting on a monitor, etc.), and their meaning is determined primarily by their shape and relative position. Color is not taken into account and is usually not used, but when using letters, their characteristics such as style and even typeface, which do not affect the meaning in ordinary writing, can play a meaningful role in mathematical notation.

Structure

Ordinary mathematical notations (in particular, the so-called mathematical formulas) are generally written in a line from left to right, but do not necessarily form a sequential string of characters. Individual blocks of characters can appear in the top or bottom half of a line, even when the characters do not overlap verticals. Also, some parts are located entirely above or below the line. From the grammatical point of view, almost any “formula” can be considered a hierarchically organized tree-type structure.

Standardization

Mathematical notation represents a system in the sense of the interconnection of its components, but, in general, Not constitute a formal system (in the understanding of mathematics itself). In any complex case, they cannot even be parsed programmatically. Like any natural language, the “language of mathematics” is full of inconsistent notations, homographs, different (among its speakers) interpretations of what is considered correct, etc. There is not even any visible alphabet of mathematical symbols, and in particular because The question of whether to consider two designations as different symbols or different spellings of the same symbol is not always clearly resolved.

Some mathematical notation (mostly related to measurement) is standardized in ISO 31-11, but overall notation standardization is rather lacking.

Elements of mathematical notation

Numbers

If it is necessary to use a number system with a base less than ten, the base is written in the subscript: 20003 8. Number systems with bases greater than ten are not used in generally accepted mathematical notation (although, of course, they are studied by science itself), since there are not enough numbers for them. In connection with the development of computer science, the hexadecimal number system has become relevant, in which the numbers from 10 to 15 are denoted by the first six Latin letters from A to F. To designate such numbers, several different approaches are used in computer science, but they have not been transferred to mathematics.

Superscript and subscript characters

Parentheses, related symbols, and delimiters

Parentheses "()" are used:

Square brackets "" are often used in grouping meanings when many pairs of brackets must be used. In this case, they are placed on the outside and (with careful typography) have a greater height than the brackets on the inside.

Square "" and parentheses "()" are used to indicate closed and open spaces, respectively.

Curly braces "()" are generally used for , although the same caveat applies to them as for square brackets. The left "(" and right ")" brackets can be used separately; their purpose is described.

Angle bracket characters " ⟨ ⟩ (\displaystyle \langle \;\rangle ) With neat typography, they should have obtuse angles and thus differ from similar ones that have a right or acute angle. In practice, one should not hope for this (especially when writing formulas manually) and one has to distinguish between them using intuition.

Pairs of symmetrical (relative to the vertical axis) symbols, including those different from those listed, are often used to highlight a piece of the formula. The purpose of paired brackets is described.

Indexes

Depending on the location, upper and lower indices are distinguished. The superscript may (but does not necessarily mean) exponentiation, about other uses.

Variables

In the sciences there are sets of quantities, and any of them can take either a set of values ​​and be called variable value (variant), or only one value and be called a constant. In mathematics, quantities are often abstracted from the physical meaning, and then the variable quantity turns into abstract(or numeric) variable, denoted by some symbol that is not occupied by the special notations mentioned above.

Variable X is considered given if the set of values ​​it accepts is specified (x). It is convenient to consider a constant quantity as a variable whose corresponding set (x) consists of one element.

Functions and Operators

In mathematics there is no significant difference between operator(unary), display And function.

However, it is understood that if to write the value of a mapping from given arguments it is necessary to specify , then the symbol of this mapping denotes a function; in other cases, they rather speak of an operator. Symbols for some functions of one argument are used with or without parentheses. Many elementary functions, for example sin ⁡ x (\displaystyle \sin x) or sin ⁡ (x) (\displaystyle \sin(x)), but elementary functions are always called functions.

Operators and relations (unary and binary)

Functions

A function can be mentioned in two senses: as an expression of its value given given arguments (written f (x) , f (x , y) (\displaystyle f(x),\ f(x,y)) etc.) or as a function itself. In the latter case, only the function symbol is inserted, without parentheses (although they are often written haphazardly).

There are many notations for common functions used in mathematical work without further explanation. Otherwise, the function must be described somehow, and in fundamental mathematics it is not fundamentally different from and is also denoted by an arbitrary letter. The most popular letter for denoting variable functions is f, g and most Greek letters are also often used.

Predefined (reserved) designations

However, single-letter designations can, if desired, be given a different meaning. For example, the letter i is often used as an index symbol in contexts where complex numbers are not used, and the letter may be used as a variable in some combinatorics. Also, set theory symbols (such as " ⊂ (\displaystyle \subset )" And " ⊃ (\displaystyle \supset )") and propositional calculi (such as " ∧ (\displaystyle \wedge)" And " ∨ (\displaystyle \vee)") can be used in another sense, usually as order relations and binary operations, respectively.

Indexing

Indexing is represented graphically (usually by bottoms, sometimes by tops) and is, in a sense, a way to expand the information content of a variable. However, it is used in three slightly different (albeit overlapping) senses.

The actual numbers

It is possible to have several different variables by denoting them with the same letter, similar to using . For example: x 1 , x 2 , x 3 … (\displaystyle x_(1),\x_(2),\x_(3)\ldots ). Usually they are connected by some kind of commonality, but in general this is not necessary.

Moreover, not only numbers, but also any symbols can be used as “indices”. However, when another variable and expression are written as an index, this entry is interpreted as “a variable with a number determined by the value of the index expression.”

In tensor analysis

In linear algebra, tensor analysis, differential geometry with indices (in the form of variables) are written

The course uses geometric language, composed of notations and symbols adopted in a mathematics course (in particular, in the new geometry course in high school).

The whole variety of designations and symbols, as well as the connections between them, can be divided into two groups:

group I - designations of geometric figures and relationships between them;

group II designations of logical operations that form the syntactic basis of the geometric language.

Below is a complete list of math symbols used in this course. Particular attention is paid to the symbols that are used to indicate the projections of geometric figures.

Group I

SYMBOLS INDICATING GEOMETRIC FIGURES AND RELATIONS BETWEEN THEM

A. Designation of geometric figures

1. A geometric figure is designated - F.

2. Points are indicated by capital letters of the Latin alphabet or Arabic numerals:

A, B, C, D, ... , L, M, N, ...

1,2,3,4,...,12,13,14,...

3. Lines arbitrarily located in relation to the projection planes are designated by lowercase letters of the Latin alphabet:

a, b, c, d, ... , l, m, n, ...

Level lines are designated: h - horizontal; f- front.

The following notations are also used for straight lines:

(AB) - a straight line passing through points A and B;

[AB) - ray with beginning at point A;

[AB] - a straight line segment bounded by points A and B.

4. Surfaces are designated by lowercase letters of the Greek alphabet:

α, β, γ, δ,...,ζ,η,ν,...

To emphasize the way a surface is defined, the geometric elements by which it is defined should be indicated, for example:

α(a || b) - the plane α is determined by parallel lines a and b;

β(d 1 d 2 gα) - the surface β is determined by the guides d 1 and d 2, the generator g and the plane of parallelism α.

5. Angles are indicated:

∠ABC - angle with vertex at point B, as well as ∠α°, ∠β°, ... , ∠φ°, ...

6. Angular: the value (degree measure) is indicated by the sign, which is placed above the angle:

The magnitude of the angle ABC;

The magnitude of the angle φ.

A right angle is marked with a square with a dot inside

7. The distances between geometric figures are indicated by two vertical segments - ||.

For example:

|AB| - the distance between points A and B (length of segment AB);

|Aa| - distance from point A to line a;

|Aα| - distances from point A to surface α;

|ab| - distance between lines a and b;

|αβ| distance between surfaces α and β.

8. For projection planes, the following designations are accepted: π 1 and π 2, where π 1 is the horizontal projection plane;

π 2 - frontal projection plane.

When replacing projection planes or introducing new planes, the latter are designated π 3, π 4, etc.

9. The projection axes are designated: x, y, z, where x is the abscissa axis; y - ordinate axis; z - applicate axis.

Monge's constant straight line diagram is denoted by k.

10. Projections of points, lines, surfaces, any geometric figure are indicated by the same letters (or numbers) as the original, with the addition of a superscript corresponding to the projection plane on which they were obtained:

A", B", C", D", ... , L", M", N", horizontal projections of points; A", B", C", D", ... , L", M" , N", ... frontal projections of points; a" , b" , c" , d" , ... , l", m" , n" , - horizontal projections of lines; a" , b" , c" , d" , ... , l" , m " , n" , ... frontal projections of lines; α", β", γ", δ",...,ζ",η",ν",... horizontal projections of surfaces; α", β", γ", δ",...,ζ" ,η",ν",... frontal projections of surfaces.

11. Traces of planes (surfaces) are designated by the same letters as horizontal or frontal, with the addition of the subscript 0α, emphasizing that these lines lie in the projection plane and belong to the plane (surface) α.

So: h 0α - horizontal trace of the plane (surface) α;

f 0α - frontal trace of the plane (surface) α.

12. Traces of straight lines (lines) are indicated by capital letters, with which the words begin that define the name (in Latin transcription) of the projection plane that the line intersects, with a subscript indicating the affiliation with the line.

For example: H a - horizontal trace of a straight line (line) a;

F a - frontal trace of straight line (line) a.

13. The sequence of points, lines (any figure) is marked with subscripts 1,2,3,..., n:

A 1, A 2, A 3,..., A n;

a 1 , a 2 , a 3 ,...,a n ;

α 1, α 2, α 3,...,α n;

Ф 1, Ф 2, Ф 3,..., Ф n, etc.

The auxiliary projection of a point, obtained as a result of transformation to obtain the actual value of a geometric figure, is denoted by the same letter with a subscript 0:

A 0 , B 0 , C 0 , D 0 , ...

Axonometric projections

14. Axonometric projections of points, lines, surfaces are denoted by the same letters as nature with the addition of a superscript 0:

A 0, B 0, C 0, D 0, ...

1 0 , 2 0 , 3 0 , 4 0 , ...

a 0 , b 0 , c 0 , d 0 , ...

α 0 , β 0 , γ 0 , δ 0 , ...

15. Secondary projections are indicated by adding a superscript 1:

A 1 0, B 1 0, C 1 0, D 1 0, ...

1 1 0 , 2 1 0 , 3 1 0 , 4 1 0 , ...

a 1 0 , b 1 0 , c 1 0 , d 1 0 , ...

α 1 0 , β 1 0 , γ 1 0 , δ 1 0 , ...

To make it easier to read the drawings in the textbook, several colors are used when designing the illustrative material, each of which has a certain semantic meaning: black lines (dots) indicate the original data; green color is used for lines of auxiliary graphic constructions; red lines (dots) show the results of constructions or those geometric elements to which special attention should be paid.

B. Symbols denoting relationships between geometric figures
No. by por. Designation Content Example of symbolic notation
1 Match(AB)≡(CD) - a straight line passing through points A and B,
coincides with the line passing through points C and D
2 Congruent∠ABC≅∠MNK - angle ABC is congruent to angle MNK
3 SimilarΔАВС∼ΔMNK - triangles АВС and MNK are similar
4 || Parallelα||β - plane α is parallel to plane β
5 Perpendiculara⊥b - straight lines a and b are perpendicular
6 Crossbreedc d - straight lines c and d intersect
7 Tangentst l - line t is tangent to line l.
βα - plane β tangent to surface α
8 DisplayedF 1 →F 2 - figure F 1 is mapped to figure F 2
9 SProjection Center.
If the projection center is an improper point,
then its position is indicated by an arrow,
indicating the direction of projection
-
10 sProjection direction -
11 PParallel projectionр s α Parallel projection - parallel projection
onto the α plane in the s direction

B. Set-theoretic notation
No. by por. Designation Content Example of symbolic notation Example of symbolic notation in geometry
1 M,NSets - -
2 A,B,C,...Elements of the set - -
3 { ... } Comprises...Ф(A, B, C,...)Ф(A, B, C,...) - figure Ф consists of points A, B, C, ...
4 Empty setL - ∅ - set L is empty (does not contain elements) -
5 Belongs to, is an element2∈N (where N is the set of natural numbers) -
the number 2 belongs to the set N
A ∈ a - point A belongs to line a
(point A lies on line a)
6 Includes, containsN⊂M - set N is part (subset) of set
M of all rational numbers
a⊂α - straight line a belongs to the plane α (understood in the sense:
the set of points of the line a is a subset of the points of the plane α)
7 An associationC = A U B - set C is a union of sets
A and B; (1, 2. 3, 4.5) = (1,2,3)∪(4.5)
ABCD = ∪ [ВС] ∪ - broken line, ABCD is
combining segments [AB], [BC],
8 Intersection of manyM=K∩L - the set M is the intersection of the sets K and L
(contains elements belonging to both the set K and the set L).
M ∩ N = ∅ - the intersection of the sets M and N is the empty set
(sets M and N do not have common elements)
a = α ∩ β - straight line a is the intersection
planes α and β
a ∩ b = ∅ - straight lines a and b do not intersect
(do not have common points)

Group II SYMBOLS INDICATING LOGICAL OPERATIONS
No. by por. Designation Content Example of symbolic notation
1 Conjunction of sentences; corresponds to the conjunction "and".
A sentence (p∧q) is true if and only if p and q are both true
α∩β = (К:K∈α∧K∈β) The intersection of surfaces α and β is a set of points (line),
consisting of all those and only those points K that belong to both the surface α and the surface β
2 Disjunction of sentences; matches the conjunction "or". Sentence (p∨q)
true when at least one of the sentences p or q is true (that is, either p or q, or both).
-
3 Implication is a logical consequence. The sentence p⇒q means: “if p, then q”(a||c∧b||c)⇒a||b. If two lines are parallel to a third, then they are parallel to each other
4 The sentence (p⇔q) is understood in the sense: “if p, then also q; if q, then also p”А∈α⇔А∈l⊂α.
A point belongs to a plane if it belongs to some line belonging to this plane.
The converse statement is also true: if a point belongs to a certain line,
belonging to the plane, then it belongs to the plane itself
5 The general quantifier reads: for everyone, for everyone, for anyone.
The expression ∀(x)P(x) means: “for every x: the property P(x) holds”
∀(ΔАВС)( = 180°) For any (for any) triangle, the sum of the values ​​of its angles
at vertices equals 180°
6 The existential quantifier reads: exists.
The expression ∃(x)P(x) means: “there is an x ​​that has the property P(x)”
(∀α)(∃a).For any plane α there is a straight line a that does not belong to the plane α
and parallel to the plane α
7 ∃1 The quantifier of the uniqueness of existence, reads: there is only one
(-i, -th)... The expression ∃1(x)(Рх) means: “there is only one (only one) x,
having the property Px"
(∀ A, B)(A≠B)(∃1a)(a∋A, B) For any two different points A and B, there is a unique straight line a,
passing through these points.
8 (Px)Negation of the statement P(x)ab(∃α)(α⊃a, b).If lines a and b intersect, then there is no plane a that contains them
9 \ Negation of the sign
≠ -segment [AB] is not equal to segment .a?b - line a is not parallel to line b

When people interact for a long time within a certain field of activity, they begin to look for a way to optimize the communication process. The system of mathematical signs and symbols is an artificial language that was developed to reduce the amount of graphically transmitted information while fully preserving the meaning of the message.

Any language requires learning, and the language of mathematics in this regard is no exception. To understand the meaning of formulas, equations and graphs, you need to have certain information in advance, understand the terms, notation system, etc. In the absence of such knowledge, the text will be perceived as written in an unfamiliar foreign language.

In accordance with the needs of society, graphic symbols for simpler mathematical operations (for example, notation for addition and subtraction) were developed earlier than for complex concepts like integral or differential. The more complex the concept, the more complex the sign it is usually denoted.

Models for the formation of graphic symbols

In the early stages of the development of civilization, people connected the simplest mathematical operations with familiar concepts based on associations. For example, in Ancient Egypt, addition and subtraction were indicated by a pattern of walking feet: lines directed in the direction of reading they indicated “plus”, and in the opposite direction - “minus”.

Numbers, perhaps in all cultures, were initially designated by the corresponding number of lines. Later, conventional notations began to be used for recording - this saved time, as well as space on physical media. Letters were often used as symbols: this strategy became widespread in Greek, Latin and many other languages ​​of the world.

The history of the emergence of mathematical symbols and signs knows two of the most productive ways of creating graphic elements.

Converting a Verbal Representation

Initially, any mathematical concept is expressed by a certain word or phrase and does not have its own graphic representation (besides the lexical one). However, performing calculations and writing formulas in words is a lengthy procedure and takes up an unreasonably large amount of space on a physical medium.

A common way to create mathematical symbols is to transform the lexical representation of a concept into a graphic element. In other words, the word denoting a concept is shortened or transformed in some other way over time.

For example, the main hypothesis for the origin of the plus sign is its abbreviation from the Latin et, the analogue of which in Russian is the conjunction “and”. Gradually, the first letter in cursive writing stopped being written, and t reduced to a cross.

Another example is the "x" sign for the unknown, which was originally an abbreviation of the Arabic word for "something". In a similar way, signs for denoting the square root, percentage, integral, logarithm, etc. appeared. In the table of mathematical symbols and signs you can find more than a dozen graphic elements that appeared in this way.

Custom character assignment

The second common option for the formation of mathematical signs and symbols is to assign the symbol in an arbitrary manner. In this case, the word and graphic designation are not related to each other - the sign is usually approved as a result of the recommendation of one of the members of the scientific community.

For example, the signs for multiplication, division, and equality were proposed by mathematicians William Oughtred, Johann Rahn and Robert Record. In some cases, several mathematical symbols may have been introduced into science by one scientist. In particular, Gottfried Wilhelm Leibniz proposed a number of symbols, including integral, differential, and derivative.

Simplest operations

Every schoolchild knows signs such as “plus” and “minus”, as well as symbols for multiplication and division, despite the fact that there are several possible graphic signs for the last two mentioned operations.

It is safe to say that people knew how to add and subtract many millennia before our era, but standardized mathematical signs and symbols denoting these actions and known to us today appeared only by the 14th-15th centuries.

However, despite the establishment of a certain agreement in the scientific community, multiplication in our time can be represented by three different signs (a diagonal cross, a dot, an asterisk), and division by two (a horizontal line with dots above and below or a slash).

Letters

For many centuries, the scientific community exclusively used Latin to communicate information, and many mathematical terms and symbols find their origins in this language. In some cases, graphic elements were the result of shortening words, less often - their intentional or accidental transformation (for example, due to a typo).

The percentage designation (“%”) most likely comes from a misspelling of the abbreviation who(cento, i.e. “hundredth part”). In a similar way, the plus sign came about, the history of which is described above.

Much more was formed by deliberate shortening of the word, although this is not always obvious. Not every person recognizes the letter in the square root sign R, i.e. the first character in the word Radix (“root”). The integral symbol also represents the first letter of the word Summa, but intuitively it looks like a capital letter f without a horizontal line. By the way, in the first publication the publishers made just such a mistake by printing f instead of this symbol.

Greek letters

Not only Latin ones are used as graphic notations for various concepts, but also in the table of mathematical symbols you can find a number of examples of such names.

The number Pi, which is the ratio of the circumference of a circle to its diameter, comes from the first letter of the Greek word for circle. There are several other lesser-known irrational numbers, denoted by letters of the Greek alphabet.

An extremely common sign in mathematics is “delta,” which reflects the amount of change in the value of variables. Another commonly used sign is “sigma”, which functions as a sum sign.

Moreover, almost all Greek letters are used in mathematics in one way or another. However, these mathematical signs and symbols and their meaning are known only to people who are engaged in science professionally. A person does not need this knowledge in everyday life.

Signs of logic

Oddly enough, many intuitive symbols were invented quite recently.

In particular, the horizontal arrow replacing the word “therefore” was proposed only in 1922. Quantifiers of existence and universality, i.e. signs read as: “there is ...” and “for any ...”, were introduced in 1897 and 1935 respectively.

Symbols from the field of set theory were invented in 1888-1889. And the crossed out circle, which is known to any high school student today as the sign of an empty set, appeared in 1939.

Thus, symbols for such complex concepts as integral or logarithm were invented centuries earlier than some intuitive symbols that are easily perceived and learned even without prior preparation.

Mathematical symbols in English

Due to the fact that a significant part of the concepts was described in scientific works in Latin, a number of names of mathematical signs and symbols in English and Russian are the same. For example: Plus, Integral, Delta function, Perpendicular, Parallel, Null.

Some concepts in the two languages ​​are called differently: for example, division is Division, multiplication is Multiplication. In rare cases, the English name for a mathematical sign becomes somewhat widespread in the Russian language: for example, the slash in recent years is often called “slash”.

symbol table

The easiest and most convenient way to familiarize yourself with the list of mathematical signs is to look at a special table that contains operation signs, symbols of mathematical logic, set theory, geometry, combinatorics, mathematical analysis, and linear algebra. This table presents the basic mathematical symbols in English.

Mathematical symbols in a text editor

When performing various types of work, it is often necessary to use formulas that use characters that are not on the computer keyboard.

Like graphic elements from almost any field of knowledge, mathematical signs and symbols in Word can be found in the “Insert” tab. In the 2003 or 2007 versions of the program, there is an “Insert Symbol” option: when you click on the button on the right side of the panel, the user will see a table that presents all the necessary mathematical symbols, Greek lowercase and uppercase letters, different types of brackets and much more.

In program versions released after 2010, a more convenient option has been developed. When you click on the “Formula” button, you go to the formula constructor, which provides for the use of fractions, entering data under the root, changing the register (to indicate powers or serial numbers of variables). All the signs from the table presented above can also be found here.

Is it worth learning math symbols?

The mathematical notation system is an artificial language that only simplifies the writing process, but cannot bring an understanding of the subject to an outside observer. Thus, memorizing signs without studying terms, rules, and logical connections between concepts will not lead to mastery of this area of ​​knowledge.

The human brain easily learns signs, letters and abbreviations - mathematical symbols are remembered by themselves when studying the subject. Understanding the meaning of each specific action creates such strong signs that the signs denoting the terms, and often the formulas associated with them, remain in memory for many years and even decades.

Finally

Since any language, including an artificial one, is open to changes and additions, the number of mathematical signs and symbols will certainly grow over time. It is possible that some elements will be replaced or adjusted, while others will be standardized in the only possible form, which is relevant, for example, for multiplication or division signs.

The ability to use mathematical symbols at the level of a full school course is practically necessary in the modern world. In the context of the rapid development of information technology and science, widespread algorithmization and automation, mastery of the mathematical apparatus should be taken for granted, and the mastery of mathematical symbols as an integral part of it.

Since calculations are used in the humanities, economics, natural sciences, and, of course, in the field of engineering and high technology, understanding mathematical concepts and knowledge of symbols will be useful for any specialist.

“Symbols are not only recordings of thoughts,
a means of depicting and consolidating it, -
no, they influence the thought itself,
they... guide her, and that’s enough
move them on paper... in order to
to unerringly reach new truths.”

L.Carnot

Mathematical signs serve primarily for precise (unambiguously defined) recording of mathematical concepts and sentences. Their totality in real conditions of their application by mathematicians constitutes what is called mathematical language.

Mathematical symbols make it possible to write in a compact form sentences that are cumbersome to express in ordinary language. This makes them easier to remember.

Before using certain signs in reasoning, the mathematician tries to say what each of them means. Otherwise they may not understand him.
But mathematicians cannot always immediately say what this or that symbol they introduced for any mathematical theory reflects. For example, for hundreds of years mathematicians operated with negative and complex numbers, but the objective meaning of these numbers and the operation with them was discovered only at the end of the 18th and beginning of the 19th centuries.

1. Symbolism of mathematical quantifiers

Like ordinary language, the language of mathematical signs allows the exchange of established mathematical truths, but being only an auxiliary tool attached to ordinary language and cannot exist without it.

Mathematical definition:

In ordinary language:

Limit of the function F (x) at some point X0 is a constant number A such that for an arbitrary number E>0 there exists a positive d(E) such that from the condition |X - X 0 |

Writing in quantifiers (in mathematical language)

2. Symbolism of mathematical signs and geometric figures.

1) Infinity is a concept used in mathematics, philosophy and science. The infinity of a concept or attribute of a certain object means that it is impossible to indicate boundaries or a quantitative measure for it. The term infinity corresponds to several different concepts, depending on the field of application, be it mathematics, physics, philosophy, theology or everyday life. In mathematics there is no single concept of infinity; it is endowed with special properties in each section. Moreover, these different "infinities" are not interchangeable. For example, set theory implies different infinities, and one may be greater than the other. Let's say the number of integers is infinitely large (it is called countable). To generalize the concept of the number of elements for infinite sets, the concept of cardinality of a set is introduced in mathematics. However, there is no one “infinite” power. For example, the power of the set of real numbers is greater than the power of integers, because one-to-one correspondence cannot be built between these sets, and integers are included in the real numbers. Thus, in this case, one cardinal number (equal to the power of the set) is “infinite” than the other. The founder of these concepts was the German mathematician Georg Cantor. In calculus, two symbols are added to the set of real numbers, plus and minus infinity, used to determine boundary values ​​and convergence. It should be noted that in this case we are not talking about “tangible” infinity, since any statement containing this symbol can be written using only finite numbers and quantifiers. These symbols (and many others) were introduced to shorten longer expressions. Infinity is also inextricably linked with the designation of the infinitely small, for example, Aristotle said:
“... it is always possible to come up with a larger number, because the number of parts into which a segment can be divided has no limit; therefore, infinity is potential, never actual, and no matter what number of divisions is given, it is always potentially possible to divide this segment into an even larger number.” Note that Aristotle made a great contribution to the awareness of infinity, dividing it into potential and actual, and from this side came closely to the foundations of mathematical analysis, also pointing to five sources of ideas about it:

  • time,
  • division of quantities,
  • the inexhaustibility of creative nature,
  • the very concept of the border, pushing beyond its limits,
  • thinking that is unstoppable.

Infinity in most cultures appeared as an abstract quantitative designation for something incomprehensibly large, applied to entities without spatial or temporal boundaries.
Further, infinity was developed in philosophy and theology along with the exact sciences. For example, in theology, the infinity of God does not so much give a quantitative definition as it means unlimited and incomprehensible. In philosophy, this is an attribute of space and time.
Modern physics comes close to the relevance of infinity denied by Aristotle - that is, accessibility in the real world, and not just in the abstract. For example, there is the concept of a singularity, closely related to black holes and the big bang theory: it is a point in spacetime at which mass in an infinitesimal volume is concentrated with infinite density. There is already solid indirect evidence for the existence of black holes, although the big bang theory is still under development.

2) A circle is a geometric locus of points on a plane, the distance from which to a given point, called the center of the circle, does not exceed a given non-negative number, called the radius of this circle. If the radius is zero, then the circle degenerates into a point. A circle is the geometric locus of points on a plane that are equidistant from a given point, called the center, at a given non-zero distance, called its radius.
The circle is a symbol of the Sun, Moon. One of the most common symbols. It is also a symbol of infinity, eternity, and perfection.

3) Square (rhombus) - is a symbol of the combination and ordering of four different elements, for example the four main elements or the four seasons. Symbol of the number 4, equality, simplicity, integrity, truth, justice, wisdom, honor. Symmetry is the idea through which a person tries to comprehend harmony and has been considered a symbol of beauty since ancient times. The so-called “figured” verses, the text of which has the outline of a rhombus, have symmetry.
The poem is a rhombus.

We -
Among the darkness.
The eye is resting.
The darkness of the night is alive.
The heart sighs greedily,
The whispers of the stars sometimes reach us.
And the azure feelings are crowded.
Everything was forgotten in the dewy brilliance.
Let's give you a fragrant kiss!
Shine quickly!
Whisper again
As then:
"Yes!"

(E.Martov, 1894)

4) Rectangle. Of all geometric forms, this is the most rational, most reliable and correct figure; empirically this is explained by the fact that the rectangle has always and everywhere been the favorite shape. With its help, a person adapted space or any object for direct use in his everyday life, for example: a house, room, table, bed, etc.

5) The Pentagon is a regular pentagon in the shape of a star, a symbol of eternity, perfection, and the universe. Pentagon - an amulet of health, a sign on the doors to ward off witches, the emblem of Thoth, Mercury, Celtic Gawain, etc., a symbol of the five wounds of Jesus Christ, prosperity, good luck among the Jews, the legendary key of Solomon; a sign of high status in Japanese society.

6) Regular hexagon, hexagon - a symbol of abundance, beauty, harmony, freedom, marriage, a symbol of the number 6, an image of a person (two arms, two legs, a head and a torso).

7) The cross is a symbol of the highest sacred values. The cross models the spiritual aspect, the ascension of the spirit, the aspiration to God, to eternity. The cross is a universal symbol of the unity of life and death.
Of course, you may not agree with these statements.
However, no one will deny that any image evokes associations in a person. But the problem is that some objects, plots or graphic elements evoke the same associations in all people (or rather, many), while others evoke completely different ones.

8) A triangle is a geometric figure that consists of three points that do not lie on the same line, and three segments connecting these three points.
Properties of a triangle as a figure: strength, immutability.
Axiom A1 of stereometry says: “Through 3 points of space that do not lie on the same straight line, a plane passes, and only one!”
To test the depth of understanding of this statement, a task is usually asked: “There are three flies sitting on the table, at three ends of the table. At a certain moment, they fly apart in three mutually perpendicular directions at the same speed. When will they be on the same plane again?” The answer is the fact that three points always, at any moment, define a single plane. And it is precisely 3 points that define the triangle, so this figure in geometry is considered the most stable and durable.
The triangle is usually referred to as a sharp, “offensive” figure associated with the masculine principle. The equilateral triangle is a masculine and solar sign representing divinity, fire, life, heart, mountain and ascension, well-being, harmony and royalty. An inverted triangle is a feminine and lunar symbol, representing water, fertility, rain, and divine mercy.

9) Six-pointed Star (Star of David) - consists of two equilateral triangles superimposed on one another. One version of the origin of the sign connects its shape with the shape of the White Lily flower, which has six petals. The flower was traditionally placed under the temple lamp, in such a way that the priest lit a fire, as it were, in the center of the Magen David. In Kabbalah, two triangles symbolize the inherent duality of man: good versus evil, spiritual versus physical, and so on. The upward-pointing triangle symbolizes our good deeds, which rise to heaven and cause a stream of grace to descend back to this world (which is symbolized by the downward-pointing triangle). Sometimes the Star of David is called the Star of the Creator and each of its six ends is associated with one of the days of the week, and the center with Saturday.
State symbols of the United States also contain the Six-Pointed Star in different forms, in particular it is on the Great Seal of the United States and on banknotes. The Star of David is depicted on the coats of arms of the German cities of Cher and Gerbstedt, as well as the Ukrainian Ternopil and Konotop. Three six-pointed stars are depicted on the flag of Burundi and represent the national motto: “Unity. Job. Progress".
In Christianity, a six-pointed star is a symbol of Christ, namely the union of the divine and human nature in Christ. That is why this sign is inscribed in the Orthodox Cross.

10) Five-pointed Star - The main distinctive emblem of the Bolsheviks is the red five-pointed star, officially installed in the spring of 1918. Initially, Bolshevik propaganda called it the “Star of Mars” (supposedly belonging to the ancient god of war - Mars), and then began to declare that “The five rays of the star mean the union of the working people of all five continents in the fight against capitalism.” In reality, the five-pointed star has nothing to do with either the militant deity Mars or the international proletariat, it is an ancient occult sign (apparently of Middle Eastern origin) called the “pentagram” or “Star of Solomon”.
Government”, which is under the complete control of Freemasonry.
Very often, Satanists draw a pentagram with both ends up so that it is easy to fit the devil’s head “Pentagram of Baphomet” there. The portrait of the “Fiery Revolutionary” is placed inside the “Pentagram of Baphomet”, which is the central part of the composition of the special Chekist order “Felix Dzerzhinsky” designed in 1932 (the project was later rejected by Stalin, who deeply hated “Iron Felix”).

Let us note that the pentagram was often placed by the Bolsheviks on Red Army uniforms, military equipment, various signs and all kinds of attributes of visual propaganda in a purely satanic way: with two “horns” up.
The Marxist plans for a “world proletarian revolution” were clearly of Masonic origin; a number of the most prominent Marxists were members of Freemasonry. L. Trotsky was one of them, and it was he who proposed making the Masonic pentagram the identifying emblem of Bolshevism.
International Masonic lodges secretly provided the Bolsheviks with full support, especially financial.

3. Masonic signs

Masons

Motto:"Freedom. Equality. Brotherhood".

A social movement of free people who, on the basis of free choice, make it possible to become better, to become closer to God, and therefore, they are recognized as improving the world.
Freemasons are comrades of the Creator, supporters of social progress, against inertia, inertia and ignorance. Outstanding representatives of Freemasonry are Nikolai Mikhailovich Karamzin, Alexander Vasilievich Suvorov, Mikhail Illarionovich Kutuzov, Alexander Sergeevich Pushkin, Joseph Goebbels.

Signs

The radiant eye (delta) is an ancient, religious sign. He says that God oversees his creations. With the image of this sign, Freemasons asked God for blessings for any grandiose actions or for their labors. The Radiant Eye is located on the pediment of the Kazan Cathedral in St. Petersburg.

The combination of a compass and a square in a Masonic sign.

For the uninitiated, this is a tool of labor (mason), and for the initiated, these are ways of understanding the world and the relationship between divine wisdom and human reason.
The square, as a rule, from below is human knowledge of the world. From the point of view of Freemasonry, a person comes into the world to understand the divine plan. And for knowledge you need tools. The most effective science in understanding the world is mathematics.
The square is the oldest mathematical instrument, known since time immemorial. Graduation of the square is already a big step forward in the mathematical tools of cognition. A person understands the world with the help of sciences; mathematics is the first of them, but not the only one.
However, the square is wooden, and it holds what it can hold. It cannot be moved apart. If you try to expand it to accommodate more, you will break it.
So people who try to understand the entire infinity of the divine plan either die or go crazy. “Know your boundaries!” - this is what this sign tells the World. Even if you were Einstein, Newton, Sakharov - the greatest minds of mankind! - understand that you are limited by the time in which you were born; in understanding the world, language, brain capacity, a variety of human limitations, the life of your body. Therefore, yes, learn, but understand that you will never fully understand!
What about the compass? The compass is divine wisdom. You can use a compass to describe a circle, but if you spread its legs, it will be a straight line. And in symbolic systems, a circle and a straight line are two opposites. The straight line denotes a person, his beginning and end (like a dash between two dates - birth and death). The circle is a symbol of deity because it is a perfect figure. They oppose each other - divine and human figures. Man is not perfect. God is perfect in everything.

For divine wisdom nothing is impossible, it can take on both a human form (-) and a divine form (0), it can contain everything. Thus, the human mind comprehends divine wisdom and embraces it. In philosophy, this statement is a postulate about absolute and relative truth.
People always know the truth, but always relative truth. And absolute truth is known only to God.
Learn more and more, realizing that you will not be able to fully understand the truth - what depths we find in an ordinary compass with a square! Who would have thought!
This is the beauty and charm of Masonic symbolism, its enormous intellectual depth.
Since the Middle Ages, the compass, as a tool for drawing perfect circles, has become a symbol of geometry, cosmic order and planned actions. At this time, the God of Hosts was often depicted in the image of the creator and architect of the Universe with a compass in his hands (William Blake “The Great Architect”, 1794).

Hexagonal Star (Bethlehem)

The letter G is the designation of God (German - Got), the great geometer of the Universe.
The Hexagonal Star meant Unity and the Struggle of Opposites, the struggle of Man and Woman, Good and Evil, Light and Darkness. One cannot exist without the other. The tension that arises between these opposites creates the world as we know it.
The upward triangle means “Man strives for God.” Triangle down - “Divinity descends to Man.” In their connection our world exists, which is the union of the Human and the Divine. The letter G here means that God lives in our world. He is truly present in everything he created.

Conclusion

Mathematical symbols serve primarily to accurately record mathematical concepts and sentences. Their totality constitutes what is called mathematical language.
The decisive force in the development of mathematical symbolism is not the “free will” of mathematicians, but the requirements of practice and mathematical research. It is real mathematical research that helps to find out which system of signs best reflects the structure of quantitative and qualitative relationships, which is why they can be an effective tool for their further use in symbols and emblems.

Select the category Books Mathematics Physics Access control and management Fire safety Useful Equipment suppliers Measuring instruments Humidity measurement - suppliers in the Russian Federation. Pressure measurement. Measuring expenses. Flow meters. Temperature measurement Level measurement. Level gauges. Trenchless technologies Sewage systems. Suppliers of pumps in the Russian Federation. Pump repair. Pipeline accessories. Butterfly valves (butterfly valves). Check valves. Control valves. Mesh filters, mud filters, magnetic-mechanical filters. Ball Valves. Pipes and pipeline elements. Seals for threads, flanges, etc. Electric motors, electric drives... Manual Alphabets, denominations, units, codes... Alphabets, incl. Greek and Latin. Symbols. Codes. Alpha, beta, gamma, delta, epsilon... Ratings of electrical networks. Conversion of units of measure Decibel. Dream. Background. Units of measurement for what? Units of measurement for pressure and vacuum. Conversion of pressure and vacuum units. Units of length. Conversion of length units (linear dimensions, distances). Volume units. Conversion of volume units. Density units. Conversion of density units. Area units. Conversion of area units. Units of hardness measurement. Conversion of hardness units. Temperature units. Conversion of temperature units in Kelvin / Celsius / Fahrenheit / Rankine / Delisle / Newton / Reamur units of measurement of angles ("angular dimensions"). Conversion of units of measurement of angular velocity and angular acceleration. Standard errors of measurements Gases are different as working media. Nitrogen N2 (refrigerant R728) Ammonia (refrigerant R717). Antifreeze. Hydrogen H^2 (refrigerant R702) Water vapor. Air (Atmosphere) Natural gas - natural gas. Biogas is sewer gas. Liquefied gas. NGL. LNG. Propane-butane. Oxygen O2 (refrigerant R732) Oils and lubricants Methane CH4 (refrigerant R50) Properties of water. Carbon monoxide CO. Carbon monoxide. Carbon dioxide CO2. (Refrigerant R744). Chlorine Cl2 Hydrogen chloride HCl, also known as hydrochloric acid. Refrigerants (refrigerants). Refrigerant (refrigerant) R11 - Fluorotrichloromethane (CFCI3) Refrigerant (Refrigerant) R12 - Difluorodichloromethane (CF2CCl2) Refrigerant (Refrigerant) R125 - Pentafluoroethane (CF2HCF3). Refrigerant (Refrigerant) R134a is 1,1,1,2-Tetrafluoroethane (CF3CFH2). Refrigerant (Refrigerant) R22 - Difluorochloromethane (CF2ClH) Refrigerant (Refrigerant) R32 - Difluoromethane (CH2F2). Refrigerant (Refrigerant) R407C - R-32 (23%) / R-125 (25%) / R-134a (52%) / Percentage by weight. other Materials - thermal properties Abrasives - grit, fineness, grinding equipment. Soils, earth, sand and other rocks. Indicators of loosening, shrinkage and density of soils and rocks. Shrinkage and loosening, loads. Angles of slope, blade. Heights of ledges, dumps. Wood. Lumber. Timber. Logs. Firewood... Ceramics. Adhesives and adhesive joints Ice and snow (water ice) Metals Aluminum and aluminum alloys Copper, bronze and brass Bronze Brass Copper (and classification of copper alloys) Nickel and alloys Correspondence of alloy grades Steels and alloys Reference tables of weights of rolled metal and pipes. +/-5% Pipe weight. Metal weight. Mechanical properties of steels. Cast Iron Minerals. Asbestos. Food products and food raw materials. Properties, etc. Link to another section of the project. Rubbers, plastics, elastomers, polymers. Detailed description of Elastomers PU, TPU, X-PU, H-PU, XH-PU, S-PU, XS-PU, T-PU, G-PU (CPU), NBR, H-NBR, FPM, EPDM, MVQ, TFE/P, POM, PA-6, TPFE-1, TPFE-2, TPFE-3, TPFE-4, TPFE-5 (PTFE modified), Strength of materials. Sopromat. Construction Materials. Physical, mechanical and thermal properties. Concrete. Concrete solution. Solution. Construction fittings. Steel and others. Material applicability tables. Chemical resistance. Temperature applicability. Corrosion resistance. Sealing materials - joint sealants. PTFE (fluoroplastic-4) and derivative materials. FUM tape. Anaerobic adhesives Non-drying (non-hardening) sealants. Silicone sealants (organosilicon). Graphite, asbestos, paronite and derivative materials Paronite. Thermally expanded graphite (TEG, TMG), compositions. Properties. Application. Production. Plumbing flax. Rubber elastomer seals. Heat insulation and thermal insulation materials. (link to project section) Engineering techniques and concepts Explosion protection. Protection from environmental influences. Corrosion. Climatic versions (Material compatibility tables) Classes of pressure, temperature, tightness Drop (loss) of pressure. — Engineering concept. Fire protection. Fires. Theory of automatic control (regulation). TAU Mathematical reference book Arithmetic, Geometric progressions and sums of some number series. Geometric figures. Properties, formulas: perimeters, areas, volumes, lengths. Triangles, Rectangles, etc. Degrees to radians. Flat figures. Properties, sides, angles, attributes, perimeters, equalities, similarities, chords, sectors, areas, etc. Areas of irregular figures, volumes of irregular bodies. Average signal magnitude. Formulas and methods for calculating area. Charts. Building graphs. Reading graphs. Integral and differential calculus. Tabular derivatives and integrals. Table of derivatives. Table of integrals. Table of antiderivatives. Find the derivative. Find the integral. Diffuras. Complex numbers. Imaginary unit. Linear algebra. (Vectors, matrices) Mathematics for the little ones. Kindergarten - 7th grade. Mathematical logic. Solving equations. Quadratic and biquadratic equations. Formulas. Methods. Solving differential equations Examples of solutions of ordinary differential equations of order higher than the first. Examples of solutions to simplest = analytically solvable first order ordinary differential equations. Coordinate systems. Rectangular Cartesian, polar, cylindrical and spherical. Two-dimensional and three-dimensional. Number systems. Numbers and digits (real, complex, ....). Number systems tables. Power series of Taylor, Maclaurin (=McLaren) and periodic Fourier series. Expansion of functions into series. Tables of logarithms and basic formulas Tables of numerical values ​​Bradis tables. Probability theory and statistics Trigonometric functions, formulas and graphs. sin, cos, tg, ctg….Values ​​of trigonometric functions. Formulas for reducing trigonometric functions. Trigonometric identities. Numerical methods Equipment - standards, sizes Household appliances, home equipment. Drainage and drainage systems. Containers, tanks, reservoirs, tanks. Instrumentation and automation Instrumentation and automation. Temperature measurement. Conveyors, belt conveyors. Containers (link) Fasteners. Laboratory equipment. Pumps and pumping stations Pumps for liquids and pulps. Engineering jargon. Dictionary. Screening. Filtration. Separation of particles through meshes and sieves. The approximate strength of ropes, cables, cords, ropes made of various plastics. Rubber products. Joints and connections. Diameters are conventional, nominal, DN, DN, NPS and NB. Metric and inch diameters. SDR. Keys and keyways. Communication standards. Signals in automation systems (instrumentation and control systems) Analog input and output signals of instruments, sensors, flow meters and automation devices. Connection interfaces. Communication protocols (communications) Telephone communications. Pipeline accessories. Taps, valves, valves... Construction lengths. Flanges and threads. Standards. Connecting dimensions. Threads. Designations, sizes, uses, types... (reference link) Connections ("hygienic", "aseptic") of pipelines in the food, dairy and pharmaceutical industries. Pipes, pipelines. Pipe diameters and other characteristics. Selection of pipeline diameter. Flow rates. Expenses. Strength. Selection tables, Pressure drop. Copper pipes. Pipe diameters and other characteristics. Polyvinyl chloride (PVC) pipes. Pipe diameters and other characteristics. Polyethylene pipes. Pipe diameters and other characteristics. HDPE polyethylene pipes. Pipe diameters and other characteristics. Steel pipes (including stainless steel). Pipe diameters and other characteristics. Steel pipe. The pipe is stainless. Stainless steel pipes. Pipe diameters and other characteristics. The pipe is stainless. Carbon steel pipes. Pipe diameters and other characteristics. Steel pipe. Fitting. Flanges according to GOST, DIN (EN 1092-1) and ANSI (ASME). Flange connection. Flange connections. Flange connection. Pipeline elements. Electric lamps Electrical connectors and wires (cables) Electric motors. Electric motors. Electrical switching devices. (Link to section) Standards for the personal life of engineers Geography for engineers. Distances, routes, maps….. Engineers in everyday life. Family, children, recreation, clothing and housing. Children of engineers. Engineers in offices. Engineers and other people. Socialization of engineers. Curiosities. Resting engineers. This shocked us. Engineers and food. Recipes, benefits. Tricks for restaurants. International trade for engineers. Let's learn to think like a huckster. Transport and travel. Personal cars, bicycles... Human physics and chemistry. Economics for engineers. Bormotology of financiers - in human language. Technological concepts and drawings Writing, drawing, office paper and envelopes. Standard photo sizes. Ventilation and air conditioning. Water supply and sewerage Hot water supply (DHW). Drinking water supply Waste water. Cold water supply Electroplating industry Refrigeration Steam lines/systems. Condensate lines/systems. Steam lines. Condensate pipelines. Food industry Natural gas supply Welding metals Symbols and designations of equipment on drawings and diagrams. Conventional graphical representations in heating, ventilation, air conditioning and heating and cooling projects, according to ANSI/ASHRAE Standard 134-2005. Sterilization of equipment and materials Heat supply Electronic industry Electricity supply Physical reference book Alphabets. Accepted notations. Basic physical constants. Humidity is absolute, relative and specific. Air humidity. Psychrometric tables. Ramzin diagrams. Time Viscosity, Reynolds Number (Re). Viscosity units. Gases. Properties of gases. Individual gas constants. Pressure and Vacuum Vacuum Length, distance, linear dimension Sound. Ultrasound. Sound absorption coefficients (link to another section) Climate. Climate data. Natural data. SNiP 01/23/99. Construction climatology. (Climate data statistics) SNIP 01/23/99. Table 3 - Average monthly and annual air temperature, °C. Former USSR. SNIP 01/23/99 Table 1. Climatic parameters of the cold period of the year. RF. SNIP 01/23/99 Table 2. Climatic parameters of the warm period of the year. Former USSR. SNIP 01/23/99 Table 2. Climatic parameters of the warm period of the year. RF. SNIP 23-01-99 Table 3. Average monthly and annual air temperature, °C. RF. SNiP 01/23/99. Table 5a* - Average monthly and annual partial pressure of water vapor, hPa = 10^2 Pa. RF. SNiP 01/23/99. Table 1. Climatic parameters of the cold season. Former USSR. Densities. Weights. Specific gravity. Bulk density. Surface tension. Solubility. Solubility of gases and solids. Light and color. Coefficients of reflection, absorption and refraction. Color alphabet:) - Designations (codings) of color (colors). Properties of cryogenic materials and media. Tables. Friction coefficients for various materials. Thermal quantities, including boiling, melting, flame, etc.... for more information, see: Adiabatic coefficients (indicators). Convection and total heat exchange. Coefficients of thermal linear expansion, thermal volumetric expansion. Temperatures, boiling, melting, other... Conversion of temperature units. Flammability. Softening temperature. Boiling points Melting points Thermal conductivity. Thermal conductivity coefficients. Thermodynamics. Specific heat of vaporization (condensation). Enthalpy of vaporization. Specific heat of combustion (calorific value). Oxygen requirement. Electrical and magnetic quantities Electrical dipole moments. The dielectric constant. Electrical constant. Electromagnetic wavelengths (reference book of another section) Magnetic field strengths Concepts and formulas for electricity and magnetism. Electrostatics. Piezoelectric modules. Electrical strength of materials Electrical current Electrical resistance and conductivity. Electronic potentials Chemical reference book "Chemical alphabet (dictionary)" - names, abbreviations, prefixes, designations of substances and compounds. Aqueous solutions and mixtures for metal processing. Aqueous solutions for applying and removing metal coatings. Aqueous solutions for cleaning from carbon deposits (asphalt-resin deposits, carbon deposits from internal combustion engines...) Aqueous solutions for passivation. Aqueous solutions for etching - removing oxides from the surface Aqueous solutions for phosphating Aqueous solutions and mixtures for chemical oxidation and coloring of metals. Aqueous solutions and mixtures for chemical polishing Degreasing aqueous solutions and organic solvents pH value. pH tables. Combustion and explosions. Oxidation and reduction. Classes, categories, designations of danger (toxicity) of chemicals. Periodic table of chemical elements by D.I. Mendeleev. Mendeleev table. Density of organic solvents (g/cm3) depending on temperature. 0-100 °C. Properties of solutions. Dissociation constants, acidity, basicity. Solubility. Mixtures. Thermal constants of substances. Enthalpies. Entropy. Gibbs energies... (link to the chemical directory of the project) Electrical engineering Regulators Systems of guaranteed and uninterrupted power supply. Dispatch and control systems Structured cabling systems Data centers