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Displaying 1021 – 1040 of 1341

On the notion of transversal of a sum of matroids

Cordovil, Raúl, Dias da Silva, J.A., Fonseca, Amélia (1988)

Portugaliae mathematica

On the null space of a Colin de Verdière matrix

Lászlo Lovász, Alexander Schrijver (1999)

Annales de l'institut Fourier

Let $G = (V, E)$ be a 3-connected planar graph, with $V = {1, ..., n}$ . Let $M = (m_{i, j})$ be a symmetric $n \times n$ matrix with exactly one negative eigenvalue (of multiplicity 1), such that for $i, j$ with $i \neq j$ , if $i$ and $j$ are adjacent then $m_{i, j} < 0$ and if $i$ and $j$ are nonadjacent then $m_{i, j} = 0$ , and such that $M$ has rank $n - 3$ . Then the null space $ker M$ of $M$ gives an embedding of $G$ in $S^{2}$ as follows: let ${a, b, c}$ be a basis of $ker M$ , and for $i \in V$ let $ϕ (i) : = (a_{i}, b_{i}, c_{i})^{T}$ ; then $ϕ (i) \neq 0$ , and $ψ (i) : = ϕ (i) / ∥ ϕ (i) ∥$ embeds $V$ in $S^{2}$ such that connecting, for any two adjacent vertices $i, j$ , the points $ψ (i)$ and $ψ (j)$ by a shortest geodesic on $S^{2}$ , gives...

On the nullity of graphs.

Cheng, Bo, Liu, Bolian (2007)

ELA. The Electronic Journal of Linear Algebra [electronic only]

On the number of 2-factors in rectangular lattice graphs.

Bodroža-Pantić, Olga, Tošić, Ratko (1994)

Publications de l'Institut Mathématique. Nouvelle Série

On the number of antichains of finite power sets

M. S. Popadić (1970)

Matematički Vesnik

On the number of complete subgraphs and circuits contained in graphs

Pál Erdös (1969)

Časopis pro pěstování matematiky

On the number of cut-vertices in a graph.

Hopkins, Glenn, Staton, William (1989)

International Journal of Mathematics and Mathematical Sciences

On the number of cycles in a graph

Frank Harary, Bennet Manvel (1971)

Matematický časopis

On the number of cycles in $k$ -connected graphs.

Knor, M. (1994)

Acta Mathematica Universitatis Comenianae. New Series

On the number of derangements of a sharply k-ply transitive set of permutations.

Werner Heise, Harald Kunde (1977)

Aequationes mathematicae

On the number of descendants and ascendants in random search trees.

Martínez, Conrado, Panholzer, Alois, Prodinger, Helmut (1998)

The Electronic Journal of Combinatorics [electronic only]

On the number of dissimilar pfaffian orientations of graphs

Marcelo H. de Carvalho, Cláudio L. Lucchesi, U. S. R. Murty (2005)

RAIRO - Theoretical Informatics and Applications - Informatique Théorique et Applications

On the number of dissimilar pfaffian orientations of graphs

Marcelo H. de Carvalho, Cláudio L. Lucchesi, U. S.R. Murty (2010)

RAIRO - Theoretical Informatics and Applications

A subgraph H of a graph G is conformal if G - V(H) has a perfect matching. An orientation D of G is Pfaffian if, for every conformal even circuit C, the number of edges of C whose directions in D agree with any prescribed sense of orientation of C is odd. A graph is Pfaffian if it has a Pfaffian orientation. Not every graph is Pfaffian. However, if G has a Pfaffian orientation D, then the determinant of the adjacency matrix of D is the square of the number of perfect matchings of G. (See the book...

Currently displaying 1021 – 1040 of 1341

Previous Page 52 Next

Displaying 1021 – 1040 of 1341

On the notion of transversal of a sum of matroids

On the null space of a Colin de Verdière matrix

On the nullity of graphs.

On the number of 2-factors in rectangular lattice graphs.

On the number of antichains of finite power sets

On the number of complete subgraphs and circuits contained in graphs

On the number of cut-vertices in a graph.

On the number of cycles in a graph

On the number of cycles in $k$ -connected graphs.

On the number of derangements of a sharply k-ply transitive set of permutations.

On the number of descendants and ascendants in random search trees.

On the number of dissimilar pfaffian orientations of graphs

On the number of dissimilar pfaffian orientations of graphs

On the number of distributive lattices.

On the Number of Faces of Simplicial Complexes and the Purity of Frobenius.

On the number of fixed points for a continuous map of a finite connected graph.

On the number of forests

On the number of fully packed loop configurations with a fixed associated matching.

On the number of genus one labeled circle trees.

On the number of independent sets in a tree.

Currently displaying 1021 – 1040 of 1341