Is $\Bbb{Z}$ compact under the evenly spaced integer topology?
The collection $$p\mathbb{Z}$$ as $p$ ranges over primes covers all but one and minus one. If I then include $$ 5\mathbb{Z}+1$$ and $$5\mathbb{Z}-1$$ has that a finite subcover?
The collection $$p\mathbb{Z}$$ as $p$ ranges over primes covers all but one and minus one. If I then include $$ 5\mathbb{Z}+1$$ and $$5\mathbb{Z}-1$$ has that a finite subcover?