In Grimaldis discrete math book he asks
Determine which of the statements are true which are false:
ℚ*∩ ℤ = ℤ
The Attempt at a Solution
he never explained in his book what * represents.
I tried google "what does Q* mean in mathematics" and "Q* in mathematics" with no luck. Does anyone know what he means with *? My first thought was its both Q+ and Q- but I dont think it is -l.-