Computer Science Background Knowledge Polynomial time approximation scheme(Ptas): an approximation scheme a that runs in time polynomial in the size of the instance 1, for any fixed a. MAX SNP-hard: unlikely to have a ptas 2021/1/29 132021/1/29 13 Computer Science Background Knowledge Polynomial time approximation scheme (PTAS): an approximation scheme A that runs in time polynomial in the size of the instance I, for any fixed . MAX SNP-hard: unlikely to have a PTAS