# Rigid components in fixed-lattice and cone frameworks

 Authors: Matthew Berardi, Brent Heeringa, Justin Malestein, and Louis Theran Proc. of: Canadian Conference on Computational Geometry CCCG’11, 2011. Full text: arXiv • URL

We study the fundamental algorithmic rigidity problems for generic frameworks periodic with respect to a fixed lattice or a finite-order rotation in the plane. For fixed-lattice frameworks we give an $O(n^2)$ algorithm for deciding generic rigidity and an $O(n^3)$ algorithm for computing rigid components. If the order of rotation is part of the input, we give an $O(n^4)$ algorithm for deciding rigidity; in the case where the rotation’s order is 3, a more specialized algorithm solves all the fundamental algorithmic rigidity problems in $O(n^2)$ time.