Question

Is P the same as P-Complete in Complexity Theory?
I need to know whether the two classes are identical. Because I have a Karp reduction between any two but can’t find it on the internet.

Answer 1

Any problem in P can be polynomial-time reduced (both many-one and
Turing) to almost any other problem in P.

The sole reason to say “almost” is because there is one problem (and
its complement) which no other problems can be many-one reduced to
(although they can be Turing reduced to): the problem that accepts
everything (and the one that rejects everything).

Source: Wikipedia