the u symbol
represents the union of two sets... its also sometimes stated as 'or' since if A and B are sets then A U B is the set of everything that is in either A or B.
not to be confused with n
where A n B is the set of everything that is in A and B
incidently {2B U ~2B} = E (the entire set... or everything) not just the question
Hope that helps, although it probably doesn't
rob
------
That statement is either so deep it would take a lifetime to fully comprehend every particle of its meaning, or it is a load of absolute tosh. Which is it, I wonder?
Terry Pratchett, Hogfather