PLS (complexity)

PLS is a syntactic subclass of TFNP. A instance of PLS can be given in terms of polynomial algorithms that determine an exponentially sized graph. Given an input x and a vertex in the graph, the polynomial algorithms can compute the neighbors of the vertex in the graph and the cost of the vertex in the graph.

An algorithm for a PLS problem, given an input x, will find a vertex in the graph such that no neighbor has better cost. This class is a subclass of TFNP, because every dag has a sink.