∑: Sum symbol.

A | 1: 1 is exactly a.

[- 1, 1]: greater than or equal to-1 and less than or equal to 1.

Leibniz, a German mathematician, thinks that "×" is very similar to the "X" in Latin letters and is easily confused in operation, so he opposes it. But he is in favor of replacing "X" with ". Therefore, the multiplication sign in German mathematics books is different from that in other countries in the world.

Extended data:

159 1 year, the French mathematician Veda used this symbol in a large number of diamonds, and it was gradually accepted by people. /kloc-In the 7th century, Leibniz in Germany widely used the symbol "=", and he also used "∽" to indicate similarity and ""to indicate congruence in geometry.

Greater than sign ">" and less than sign "

Any number (full name quantifier)? Derived from the English word Arbitrary, because lowercase and uppercase are easily confused, the first letter of the word is capitalized and then inverted. Similarly, existential number (existential quantifier)? Reverse writing of e from the word Exist.

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