{ "id": "1412.1004", "version": "v1", "published": "2014-12-02T18:21:09.000Z", "updated": "2014-12-02T18:21:09.000Z", "title": "On rigidity, orientability and cores of random graphs with sliders", "authors": [ "Julien Barré", "Marc Lelarge", "Dieter Mitsche" ], "comment": "29 pages, 1 figure", "categories": [ "math.CO", "math.PR" ], "abstract": "Suppose that you add rigid bars between points in the plane, and suppose that a constant fraction $q$ of the points moves freely in the whole plane; the remaining fraction is constrained to move on fixed lines called sliders. When does a giant rigid cluster emerge? Under a genericity condition, the answer only depends on the graph formed by the points (vertices) and the bars (edges). We find for the random graph $G \\in \\mathcal{G}(n,c/n)$ the threshold value of $c$ for the appearance of a linear-sized rigid component as a function of $q$, generalizing results of Kasiviswanathan et al. We show that this appearance of a giant component undergoes a continuous transition for $q \\leq 1/2$ and a discontinuous transition for $q > 1/2$. In our proofs, we introduce a generalized notion of orientability interpolating between 1- and 2-orientability, of cores interpolating between 2-core and 3-core, and of extended cores interpolating between 2+1-core and 3+2-core; we find the precise expressions for the respective thresholds and the sizes of the different cores above the threshold. In particular, this proves a conjecture of Kasiviswanathan et al. about the size of the 3+2-core. We also derive some structural properties of rigidity with sliders (matroid and decomposition into components) which can be of independent interest.", "revisions": [ { "version": "v1", "updated": "2014-12-02T18:21:09.000Z" } ], "analyses": { "keywords": [ "random graph", "orientability", "giant rigid cluster emerge", "giant component undergoes", "add rigid bars" ], "note": { "typesetting": "TeX", "pages": 29, "language": "en", "license": "arXiv", "status": "editable", "adsabs": "2014arXiv1412.1004B" } } }