Checkers, also called draughts, is a family of two-player games played on a checkerboard. English
draughts, also called American checkers, is played on an checkerboard with
twelve pieces per player (World Checkers/Draughts Federation). International draughts
is played on a checkerboard with twenty pieces per player (World Draughts
Federation). The board size and rules therefore depend on the variant.
Pool checkers, also called Spanish pool checkers, is a distinct variant. Unlike English
draughts, it allows uncrowned pieces to capture backwards and crowned pieces
to move any distance along an unobstructed diagonal (Ratrout 2018, p. 12).
Checkers sets commonly have black and red boards and pieces.
The official colors depend on the variant and its governing federation.
The numbers 1, 40, 793, 12800, 193721, ... (OEIS A006240) and 1, 13, 108, 793, 5611, 39312, ... (OEIS A006239)
count Eulerian circuits in the graph
Cartesian product of two directed cycle graphs
of lengths 4 and ,
and 3 and ,
respectively. They do not count two different conventions for circuits on the same
square checkerboard.
checkerboard with
twelve pieces per player (World Checkers/Draughts Federation). International draughts
is played on a 
checkerboard with twenty pieces per player (World Draughts
Federation). The board size and rules therefore depend on the variant.
variant. Unlike English
draughts, it allows uncrowned pieces to capture backwards and crowned pieces
to move any distance along an unobstructed diagonal (Ratrout 2018, p. 12).
,
and 3 and 
,
respectively. They do not count two different conventions for circuits on the same
square checkerboard.
