Abstract
Fan Chung and Ron Graham (J. Combin. Theory Ser. B 65 (1995) 273–290) introduced the cover polynomial for a directed graph and showed that it was connected with classical rook theory. Dworkin (J. Combin. Theory Ser. B 71 (1997) 17–53) showed that the cover polynomial naturally factors for directed graphs associated with Ferrers boards. The authors (Adv. Appl. Math. 27 (2001) 438–481) developed a rook theory for shifted Ferrers boards where the analogue of a rook placement is replaced by a partial perfect matching of K 2 n , the complete graph on 2 n vertices. In this paper, we show that an analogue of Dworkin's result holds for shifted Ferrers boards in this setting. We also show how cycle-counting matching numbers are connected to cycle-counting “hit numbers” (which involve perfect matchings of K 2 n ).
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