Polynomial Time Reducibility
Informal idea: A decision problem A is polynomial time reducible to a decision problem B if a polynomial time algorithm for B can be used to construct a polynomial time algorithm for A.
Formally: A is polynomial time reducible to B if there is a function f computable in polynomial time such that for all x:
- x has A if and only if f(x) has B
If A polynomial time reducible to B and B solvable in polynomial time then so is A.