Compression Theorems for Periodic Tilings and Consequences
Arthur T. Benjamin
Department of Mathematics
Harvey Mudd College
Claremont, CA 91711 USA
Alex K. Eustis
Department of Mathematics
UC San Diego
La Jolla, CA 92037 USA
Mark A. Shattuck
Department of Mathematics
University of Tennessee
Knoxville, TN 37996 USA
Abstract:
We consider a weighted square-and-domino tiling model obtained by
assigning real number weights to the cells and boundaries of an
n-board. An important special case apparently arises when these
weights form periodic sequences. When the weights of an
nm-tiling form sequences having period m, it is shown that
such a tiling may be regarded as a meta-tiling of length n whose
weights have period 1 except for the first cell (i.e., are
constant). We term such a contraction of the period in going from
the longer to the shorter tiling as "period compression". It
turns out that period compression allows one to provide
combinatorial interpretations for certain identities involving
continued fractions as well as for several identities involving
Fibonacci and Lucas numbers (and their generalizations).
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(Concerned with sequences
A000032
and
A000045.)
Received January 27 2009;
revised version received August 2 2009.
Published in Journal of Integer Sequences, August 30 2009.
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