Question

what does this symbol mean in math?
http://i45.tinypic.com/35k200h.jpg

Answer 1

the V and the other one turned upside down? ?

Answer 2

The way I've seen it used,V means union of sets and upside down triangle means intersection of sets.

Answer 3

apparently there's a DIFFERENT meaning :|

Answer 4

OK i'm leaning this: http://i47.tinypic.com/dxhdm8.jpg. the text means.
Set X C R is lower-bounded if:....then that image i posted earlier. in this context what do the V and upside V mean?

Answer 5

\[\Large\bigvee_{m\in \mathbb R}\bigwedge_{x\in X}x\geq m\]

\(x\) is greater than or equal to \(m\) ,
OR \(m\) is an element of the real numbers ,
And \(x\) is in the set \(X\) .

Answer 6

\(\land\) and

\(\lor\) or

Answer 7

\[X\subset\mathbb R\]
the set \(X\) is a subset of the real numbers

Answer 8

@Rudy

\(A\cup B\) is the union of sets \(A, B\)

\(A\cap B\) is the intersection

Answer 9

@tomiko I don't understand the language, but it seems 'real analysis' and I guess that it supposed to be, Set \[X \subset R\] is bounded from below, or have a lower bound if
\[\forall m \in R, \exists x \in X, x \ge m\]

we can say that, for all m in R, there exist x in X such that x greater than or equal to m,
that's the usual symbol that I know... :)

Answer 10

@chihiroasleaf exactly what i wanted!! thank to @UnkleRhaukus too!!

Answer 11

but I think, \[X \subset R\] is said to have a lower bound if \[\exists m \in R,\] such that \[\forall x \in R \rightarrow x \ge m \]

Answer 12

the fancy names are conjunctions (and) , disjunction (or)

Answer 13

yes.., they usually use for logic, it's my first time see these symbol use in this subject... :D

Answer 14

but this is NOT logic. i know what they mean in logic. usually the in logic the "v" i smaller. but this one the "V" is very big and under it they write something like x is a member of R. this is definitely not logic.

Answer 15

yes.., that's why I say that it's my first time see these symbol are used in this subject, but the definition is a bit different to what I know, may be you can read on this link about upper and lower bound of a set...
If I refer to the usual definition of upper and lower bound than, V will mean 'there exist' and '^' will mean 'for all'
http://www.emathzone.com/tutorials/real-analysis/upper-and-lower-bounds.html

Answer 16

so, your image will mean
\[\exists m \in R, \forall x \in X, x \ge m\]
it will make sense if, we are talking about lower bound...
sorry for the mistake...

Answer 17

@tomiko