General topology

[aymane amine]

why isnt (-1/n,1/n) not an open in the product topology but open in the box topology ?

[Country Boy]

Your double negative is a little confusing!  Also, by "(-1/n, 1/n)" so you mean the interval or the pair of numbers.  If the first, what "product topology" are you talking about?  If the latter, that's a single point, not a set.

[uncool]

I'm guessing they mean the product in the infinite product of the real line. 

 

Have you tried applying the definitions of the two topologies?