Journal of Integer Sequences, Vol. 28 (2025), Article 25.8.6

Counting Nonattacking Chess Piece Placements: Bishops and Anassas


Eder G. Santos
Brazil

Abstract:

We derive recurrences and closed-form expressions for counting nonattacking placements of two types of chess pieces with unbounded straight-line moves, namely the bishop (two diagonal moves) and the anassa (one horizontal or vertical move and one diagonal move), placed on a standard square chessboard. Additionally, we obtain explicit expressions for the corresponding quasi-polynomial coefficients. The recurrences are derived by analyzing how nonattacking configurations attack a specific subset of board squares, employing a bijective argument to establish the relations. The main results are simplifications of known expressions for the bishop and a general counting formula for the anassa.


Full version:  pdf,    dvi,    ps,    latex    


(Concerned with sequences A008277 A008299 A132393 A134991 A274105 A274106 A378561 A378590.)


Received January 22 2025; revised versions received January 30 2025; April 28 2025. Published in Journal of Integer Sequences, December 15 2025.


Return to Journal of Integer Sequences home page