What is these symbols meaning?

mathematical symbols?

See here Wikipedia, they look like, can be...

Tomás

in your mail CR4 y send you

External links

• Jeff Miller: Earliest Uses of Various Mathematical Symbols
• TCAEP - Institute of Physics
• GIF and PNG Images for Math Symbols

Row 1

1st symbol = 'the universal qualifier'= 'for every' or 'for all'

2nd symbol='the existential qualifier'='there exists'

It is tricky to explain without a full uasage of the symbol.I will try to paste an example sometime today ,if it is not done so before by someone who knows how to get symbles on the screen. Meantime looking up the phrases in ' ' may help.

We cannt entry into this Wikipedia web site from our mainland.

it was blocked by our some department, I was told. because some politics cause.

In boolean algebra, there maybe some like them.

But I hvnt ever studied hardly it. I know only simple algorithm.

as well as set theory.

these are normal use in books

∨∪∈≮∈

now I rewrite as left. where A is a set, x is veriable , what means are they?

no. 1 is

There exists an x ,belonging to A , for which the proposition p(x) is valid.

and no. 2 is

For every x ,belonging to A , p(x) is valid

p(x) is the proposition.

Set theory and notation is not really my thing , but I hope the above helps.

Thank you all, Tesla offer a very useful site at

http://members.aol.com/jeff570/set.html

and Kris's explain is right.

I abstract one peragraph as follow, which explain all,

[For all. According to M. J. Cresswell and Irving H. Anellis, originated in Gerhard Gentzen, "Untersuchungen ueber das logische Schliessen," Math. Z., 39, (1935), p, 178. In footnote 4 on that page, Gentzen explains how he came to use the sign. It is the "All-Zeichen," an analogy with for the existential quantifier which Gentzen says that he borrowed from Russell. ]

The original "Set Theory" (c.1900) was very promising at first, after Georg Cantor's concept invented, later was considered non coherent because of Russell's paradox, and other found inconsistencies called Antimonies.

This later led to development of the more confined and parallel theories: Axiomal Set theory, still debated today, and the Naive Set theory, the most widely used today, for the insemination of the foundation to math and logic.