OFFSET
1,2
COMMENTS
Equivalently, one-sided poly-IH13-tiles or one-sided poly-IH15-tiles. IH4 is the generic isohedral tiling by 180-degree rotation (Conway criterion).
REFERENCES
Branko Grünbaum and G. C. Shephard, Tilings and Patterns. W. H. Freeman, New York, 1987, Sections 6.2 and 9.4.
CROSSREFS
KEYWORD
hard,nonn
AUTHOR
Joseph Myers, Oct 19 2011
STATUS
approved