منابع مشابه
Generalizations of Matroid Duality
Matroid duality is an important generalization of duality for planar graphs. Using unpublished notes of Brylawski, we extend this notion to arbitrary set systems. This allows one to define a generalized Tutte polynomial. We examine this polynomial for several set systems that are not matroids, and we also investigate the combinatorial significance of duality for these set systems.
متن کاملFenchel-type duality for matroid valuations
The weighted matroid intersection problem has recently been extended to the valuated matroid intersection problem: Given a pair of valuated matroids Mi = (V,Bi, ωi) (i = 1, 2) defined on a common ground set V , find a common base B ∈ B1∩B2 that maximizes ω1(B)+ω2(B). This paper develops a Fenchel-type duality theory related to this problem with a view to establishing a convexity framework for n...
متن کاملMatroid Duality From Topological Duality In Surfaces Of Nonnegative Euler Characteristic
One of the most basic examples of matroid duality is the following. Let G be a graph imbedded in the plane and let G∗ be its topological dual graph. If M(G) is the cycle matroid of G, then the dual matroid M∗(G) = M(G∗). If G is a connected graph that is 2-cell imbedded in a surface of demigenus d > 0 (the demigenus is equal to 2 minus the euler characteristic of the surface), then M∗(G) 6= M(G...
متن کاملPenile Erection
Hemodynamic Aspects Penile erection and detumescence are primari ly controlled by hemodynamic events. Increased arterial inflow appears to be of primary importance; the contribution of increased venous resistance to the production of penile erection remains controversial. Furthermore, our understanding of precise anatomic details ( including “shunts”) and the neural control of vascular events i...
متن کاملOn a new G-frame and duality
We introduce a new g-frame (singleton g-frame), g-orthonormal basis and g-Riesz basis and study corresponding notions in some other generalizations of frames.Also, we investigate duality for some kinds of g-frames. Finally, we illustrate an example which provides a suitable translation from discrete frames to Sun's g-frames.
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
ژورنال
عنوان ژورنال: European Journal of Combinatorics
سال: 1987
ISSN: 0195-6698
DOI: 10.1016/s0195-6698(87)80044-6