Results 21 to 30 of about 339 (75)
Homotopy type of the complex of free factors of a free group
Proceedings of the London Mathematical Society, Volume 121, Issue 6, Page 1737-1765, December 2020., 2020 Abstract We show that the complex of free factors of a free group of rank n⩾2 is homotopy equivalent to a wedge of spheres of dimension n−2. We also prove that for n⩾2, the complement of (unreduced) Outer space in the free splitting complex is homotopy equivalent to the complex of free factor systems and moreover is (n−2)‐connected.
Benjamin Brück, Radhika Gupta
wiley +1 more source
When products of projections diverge
Journal of the London Mathematical Society, Volume 102, Issue 1, Page 345-367, August 2020., 2020 Abstract Slow convergence of cyclic projections implies divergence of random projections and vice versa. Let L1,L2,⋯,LK be a family of K closed subspaces of a Hilbert space. It is well known that although the cyclic product of the orthogonal projections on these spaces always converges in norm, random products might diverge.
Eva Kopecká
wiley +1 more source
Decomposing tournaments into paths
Proceedings of the London Mathematical Society, Volume 121, Issue 2, Page 426-461, August 2020., 2020 Abstract We consider a generalisation of Kelly's conjecture which is due to Alspach, Mason, and Pullman from 1976. Kelly's conjecture states that every regular tournament has an edge decomposition into Hamilton cycles, and this was proved by Kühn and Osthus for large tournaments. The conjecture of Alspach, Mason, and Pullman asks for the minimum number
Allan Lo +3 more
wiley +1 more source
Untwisting 3‐strand torus knots
Bulletin of the London Mathematical Society, Volume 52, Issue 3, Page 429-436, June 2020., 2020 Abstract We prove that the signature bound for the topological 4‐genus of 3‐strand torus knots is sharp, using McCoy's twisting method. We also show that the bound is off by at most 1 for 4‐strand and 6‐strand torus knots, and improve the upper bound on the asymptotic ratio between the topological 4‐genus and the Seifert genus of torus knots from 2/3 ...
S. Baader, I. Banfield, L. Lewark
wiley +1 more source
Game-Theoretic Approach for Solving Multiobjective Flow Problems on Networks [PDF]
Computer Science Journal of Moldova, 2005 The game-theoretic formulation of the multiobjective multicommodity flow problem is considered. The dynamic version of this problem is studied and an algorithm for its solving, based on the concept of multiobjective games, is proposed.
Maria A. Fonoberova, Dmitrii D. Lozovanu
doaj
Valid inequalities and cutting planes for some polytopes
, 1998 In this paper we consider multidimensional knapsack polytope. Some important concepts and preliminaries are given at the beginning. Then we give a result connected with valid and dominating inequalities for this polytope, and a modular arithmetic ...
S. Stefanov
semanticscholar +1 more source
Location of zeros for the partition function of the Ising model on bounded degree graphs
Journal of the London Mathematical Society, Volume 101, Issue 2, Page 765-785, April 2020., 2020 Abstract The seminal Lee–Yang theorem states that for any graph the zeros of the partition function of the ferromagnetic Ising model lie on the unit circle in C. In fact, the union of the zeros of all graphs is dense on the unit circle. In this paper, we study the location of the zeros for the class of graphs of bounded maximum degree d⩾3, both in the ...
Han Peters, Guus Regts
wiley +1 more source
Algorithms for minimum flows [PDF]
Computer Science Journal of Moldova, 2001 We present a generic preflow algorithm and several implementations of it, that solve the minimum flow problem in O(n2m) time.
Eleonor Ciurea, Laura Ciupal
doaj
The maximum flow in dynamic networks [PDF]
Computer Science Journal of Moldova, 2005 The dynamic maximum flow problem that generalizes the static maximum flow problem is formulated and studied. We consider the problem on a network with capacities depending on time, fixed transit times on the arcs, and a given time horizon.
Maria A. Fonoberova, Dmitrii D. Lozovanu
doaj
Sum-of-squares clustering on networks [PDF]
, 2011 Finding p prototypes by minimizing the sum of the squared distances from a set of points to its closest prototype is a well-studied problem in clustering, data analysis and continuous location. In this note, this very same problem is addressed assuming,
Carrizosa Priego, Emilio José +2 more
core +2 more sources