Abstract
Given a periodic graph, we wish to determine via combinatorial methods whether it has periodic embeddings in the plane that—via motions that preserve edge-lengths and periodicity—can be continuously deformed into another non-congruent embedding of the graph. By introducing NBAC-colourings for the corresponding quotient gain graphs, we identify which periodic graphs have flexible embeddings in the plane when the lattice of periodicity is fixed. We further characterise with NBAC-colourings which 1-periodic graphs have flexible embeddings in the plane with a flexible lattice of periodicity, and characterise in special cases which 2-periodic graphs have flexible embeddings in the plane with a flexible lattice of periodicity.
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Notes
Although (G, p) is the standard notation for a framework, we shall instead reserve this for the quotient frameworks that we use throughout the majority of this paper.
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I would like to thank the anonymous referees for their valuable corrections and comments, all of which helped greatly to improve the paper.
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Dewar, S. Flexible Placements of Periodic Graphs in the Plane. Discrete Comput Geom 66, 1286–1329 (2021). https://doi.org/10.1007/s00454-021-00328-x
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DOI: https://doi.org/10.1007/s00454-021-00328-x