41 research outputs found

    Counting outerplanar maps

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    A map is outerplanar if all its vertices lie in the outer face. We enumerate various classes of rooted outerplanar maps with respect to the number of edges and vertices. The proofs involve several bijections with lattice paths. As a consequence of our results, we obtain an e cient scheme for encoding simple outerplanar maps.Peer ReviewedPostprint (published version

    Enumeration and random generation of planar maps

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    This works gives some results on outerplanar maps, which includes a codification of simple outerplanar maps with 3n bits, where n is the number of nodes. It also includes an algorithm to produce random generated maps with equal probability

    Unified bijections for planar hypermaps with general cycle-length constraints

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    We present a general bijective approach to planar hypermaps with two main results. First we obtain unified bijections for all classes of maps or hypermaps defined by face-degree constraints and girth constraints. To any such class we associate bijectively a class of plane trees characterized by local constraints. This unifies and greatly generalizes several bijections for maps and hypermaps. Second, we present yet another level of generalization of the bijective approach by considering classes of maps with non-uniform girth constraints. More precisely, we consider "well-charged maps", which are maps with an assignment of "charges" (real numbers) on vertices and faces, with the constraints that the length of any cycle of the map is at least equal to the sum of the charges of the vertices and faces enclosed by the cycle. We obtain a bijection between charged hypermaps and a class of plane trees characterized by local constraints

    The geometry of large outerplanar and half-planar maps

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    Graph limits of random graphs from a subset of connected kk-trees

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    For any set Ω\Omega of non-negative integers such that {0,1}⊆Ω\{0,1\}\subseteq \Omega and {0,1}≠Ω\{0,1\}\ne \Omega, we consider a random Ω\Omega-kk-tree Gn,k{\sf G}_{n,k} that is uniformly selected from all connected kk-trees of (n+k)(n+k) vertices where the number of (k+1)(k+1)-cliques that contain any fixed kk-clique belongs to Ω\Omega. We prove that Gn,k{\sf G}_{n,k}, scaled by (kHkσΩ)/(2n)(kH_{k}\sigma_{\Omega})/(2\sqrt{n}) where HkH_{k} is the kk-th Harmonic number and σΩ>0\sigma_{\Omega}>0, converges to the Continuum Random Tree Te\mathcal{T}_{{\sf e}}. Furthermore, we prove the local convergence of the rooted random Ω\Omega-kk-tree Gn,k∘{\sf G}_{n,k}^{\circ} to an infinite but locally finite random Ω\Omega-kk-tree G∞,k{\sf G}_{\infty,k}.Comment: 21 pages, 6 figure
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