  We prove that Strings-and-Coins -- the combinatorial two-player game
generalizing the dual of Dots-and-Boxes -- is strongly PSPACE-complete on
multigraphs. This result improves the best previous result, NP-hardness, argued
in Winning Ways. Our result also applies to the Nimstring variant, where the
winner is determined by normal play; indeed, one step in our reduction is the
standard reduction (also from Winning Ways) from Nimstring to
Strings-and-Coins.
