Of course it is required (within the computational limits of your computer, of course) If p(x) means 'x is an integer', you could use the regex /^1$/ since it

Of course it is required (within the computational limits of your computer, of course) If p(x) means 'x is an integer', you could use the regex /^1$/ since it matches integers only (in particular, the integer 1). That's not sufficient, you need to match all integers. edited:format