English

Perfect domination in rectangular grid graphs

Combinatorics 2007-11-28 v1

Abstract

A dominating set SS in a graph GG is said to be perfect if every vertex of GG not in SS is adjacent to just one vertex of SS. Given a vertex subset SS' of a side PmP_m of an m×nm\times n grid graph GG, the perfect dominating sets SS in GG with S=SV(Pm)S'=S\cap V(P_m) can be determined via an exhaustive algorithm Θ\Theta of running time O(2m+n)O(2^{m+n}). Extending Θ\Theta to infinite grid graphs of width m1m-1, periodicity makes the binary decision tree of Θ\Theta prunable into a finite threaded tree, a closed walk of which yields all such sets SS. The graphs induced by the complements of such sets SS can be codified by arrays of ordered pairs of positive integers via Θ\Theta, for the growth and determination of which a speedier %greedy algorithm exists. %and their periodic structure, further studied. A recent characterization of grid graphs having total perfect codes SS (with just 1-cubes as induced components), due to Klostermeyer and Goldwasser, is given in terms of Θ\Theta, which allows to show that these sets SS are restrictions of only one total perfect code S1S_1 in the integer lattice graph Λ{\Lambda} of R2\R^2. Moreover, the complement ΛS1{\Lambda}-S_1 yields an aperiodic tiling, like the Penrose tiling. In contrast, the parallel, horizontal, total perfect codes in Λ{\Lambda} are in 1-1 correspondence with the doubly infinite {0,1}\{0,1\}-sequences.

Keywords

Cite

@article{arxiv.0711.4345,
  title  = {Perfect domination in rectangular grid graphs},
  author = {Italo J. Dejter and Abel A. Delgado},
  journal= {arXiv preprint arXiv:0711.4345},
  year   = {2007}
}

Comments

21 pages; 3 figures; accepted for publication in JCMCC

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