Weakly submodular rank functions, supermatroids, and the flat lattice of a distributive supermatroid
نویسندگان
چکیده
منابع مشابه
Weakly submodular rank functions, supermatroids, and the flat lattice of a distributive supermatroid
Distributive supermatroids generalize matroids to partially ordered sets. Completing earlier work of Barnabei, Nicoletti and Pezzoli we characterize the lattice of flats of a distributive supermatroid. For the prominent special case of a polymatroid the description of the flat lattice is particularly simple. Large portions of the proofs reduce to properties of weakly submodular rank functions. ...
متن کاملWeakly Submodular Functions
Submodular functions arewell-studied in combinatorial optimization, game theory and economics. The natural diminishing returns property makes them suitable for many applications. We study an extension of monotone submodular functions, which we call weakly submodular functions. Our extension is somewhat unusual in that it includes some (mildly) supermodular functions. We show that several natura...
متن کاملTotal graph of a $0$-distributive lattice
Let £ be a $0$-distributive lattice with the least element $0$, the greatest element $1$, and ${rm Z}(£)$ its set of zero-divisors. In this paper, we introduce the total graph of £, denoted by ${rm T}(G (£))$. It is the graph with all elements of £ as vertices, and for distinct $x, y in £$, the vertices $x$ and $y$ are adjacent if and only if $x vee y in {rm Z}(£)$. The basic properties of the ...
متن کاملA Note on Submodular Functions on Distributive Lattices
A NOTE ON SUBMODULAR FUNCTIONS ON DISTRIBUTIVE LATTICES Satoru Fujishige University of Tsukuba Nobuaki Tomizawa Niigata University (Received July 15, 1982; Rllvised June 14, 1983) Let D be a distributive lattice formed by subsets of a finite set E with 1/>, E E D and let R be the set of reals. Also let f be a submodular function from D into R with f(l/» = O. We determine the set of extreme poin...
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: Discrete Mathematics
سال: 2008
ISSN: 0012-365X
DOI: 10.1016/j.disc.2007.03.023