## Abstract

For a finite point set *E* ⊂ ℝ^{d} and a connected graph *G* on *k* + 1 vertices, we define a *G*-framework to be a collection of *k* + 1 points in *E* such that the distance between a pair of points is specified if the corresponding vertices of G are connected by an edge. We consider two frameworks the same if the specified edge-distances are the same. We find tight bounds on such distinct-distance drawings for rigid graphs in the plane, deploying the celebrated result of Guth and Katz. We introduce a congruence relation on a wider set of graphs, which behaves nicely in both the real-discrete and continuous settings. We provide a sharp bound on the number of such congruence classes. We then make a conjecture that the tight bound on rigid graphs should apply to all graphs. This appears to be a hard problem even in the case of the nonrigid 2-chain. However, we provide evidence to support the conjecture by demonstrating that if the Erd˝os pinned-distance conjecture holds in dimension d, then the result for all graphs in dimension d follows.

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Published in Russian in Trudy Matematicheskogo Instituta imeni V.A. Steklova, 2018, Vol. 303, pp. 142–154.

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Iosevich, A., Passant, J. Finite Point Configurations in the Plane, Rigidity and Erdős Problems.
*Proc. Steklov Inst. Math.* **303**, 129–139 (2018). https://doi.org/10.1134/S0081543818080114

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DOI: https://doi.org/10.1134/S0081543818080114