5 research outputs found
Counting Lattice Animals in High Dimensions
We present an implementation of Redelemeier's algorithm for the enumeration
of lattice animals in high dimensional lattices. The implementation is lean and
fast enough to allow us to extend the existing tables of animal counts,
perimeter polynomials and series expansion coefficients in -dimensional
hypercubic lattices for . From the data we compute formulas
for perimeter polynomials for lattice animals of size in arbitrary
dimension . When amended by combinatorial arguments, the new data suffices
to yield explicit formulas for the number of lattice animals of size
and arbitrary . We also use the enumeration data to compute numerical
estimates for growth rates and exponents in high dimensions that agree very
well with Monte Carlo simulations and recent predictions from field theory.Comment: 18 pages, 7 figures, 6 tables; journal versio
A new mathematical model for tiling finite regions of the plane with polyominoes
We present a new mathematical model for tiling finite subsets of using an arbitrary, but finite, collection of polyominoes. Unlike previous approaches that employ backtracking and other refinements of `brute-force' techniques, our method is based on a systematic algebraic approach, leading in most cases to an underdetermined system of linear equations to solve. The resulting linear system is a binary linear programming problem, which can be solved via direct solution techniques, or using well-known optimization routines.
We illustrate our model with some numerical examples computed in MATLAB. Users can download, edit, and run the codes from http://people.sc.fsu.edu/~jburkardt/m_src/polyominoes/polyominoes.html. For larger problems we solve the resulting binary linear programming problem with an optimization package such as CPLEX, GUROBI, or SCIP, before plotting solutions in MATLAB