Given the set S={(x,y): |x|<1 , |y|<1} prove that is open in .

Using the definition of the open set we have:

S is open in iff for all ,there exists an ε>0 such that ,for all :

.

.......................................OR......... ..................................................

if ,there exists an ε>0 such that:

What is the epsilon ,so that the implication can be satisfied ??

That is as far i can go.

Any suggestions??