∑ is a summation symbol, English name: sigma, Chinese name: Sigma (capital σ, lowercase σ), the18th Greek letter. In Greek, if the last letter of a word is lowercase sigma, it should be written as? This letter is also called final sigma(Unicode: U+03C2).
What other symbols are there in mathematics?
I. Geometric symbols
Geometry is the study of spatial structure and properties. It is one of the most basic research contents in mathematics, and the common theorems are Pythagorean Theorem, euler theorem Theorem and Stewart Theorem. Common symbols are ⊥ (vertical), ∨ (parallel), ∞ (angle), ⌒ (arc) and ⊙ (circle).
Second, algebraic symbols
The research object of algebra is not only numbers, but various abstract structures. Among them, we only care about various relationships and their nature, but we don't care about the question "what is the number itself".
Common symbols are: ∧ (proportion), ∧ (logical sum), ∨ (logical OR), ∫ (integer), ≦ (inequality), ≤ (less than or equal to), ≥ (greater than or equal to), ≈ (approximately equal to) and ∞ (infinity).
Third, the operation symbol
Operational symbols are symbols used in computational mathematics, and computational symbols include plus sign, minus sign, multiplication sign and division sign. Common symbols are: × (multiplication), ⊙ (division), √ (root sign) and (addition and subtraction).
Fourth, collect symbols.
A collection refers to a collection of concrete or abstract objects with certain attributes, which are called elements of a collection. On the whole, certain, definite and distinguishable things are called sets, or sets for short.
Common symbols are ∩ (union), ∩ (intersection) and ∈ (attribution).
Verb (abbreviation of verb) special symbol
A specific symbol is often used in mathematics to represent an element. Common symbols are ∑ (sum) and π (pi).
Six, Greek symbols
In mathematics, Greek letters are usually used to represent constants, special functions and some specific variables. In the field of mathematics, the meanings of uppercase and lowercase Greek letters are usually different and irrelevant.