Graphs Admitting $k$-NU Operations. Part 1: The Reflexive Case

نویسندگان
چکیده

برای دانلود رایگان متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

منابع مشابه

Graphs Admitting k-NU Operations. Part 1: The Reflexive Case

We describe a generating set for the variety of reflexive graphs that admit a compatible k-ary near-unanimity operation; we further delin-eate a very simple subset that generates the variety of j-absolute retracts; in particular we show that the class of reflexive graphs with a 4-NU operation coincides with the class of 3-absolute retracts. Our results generalise and encompass several results o...

متن کامل

Graphs Admitting k-NU Operations. Part 2: The Irreflexive Case

We describe a generating set for the variety of simple graphs that admit a k-ary near-unanimity polymorphism. The result follows from an analysis of NU polymorphisms of strongly bipartite digraphs, i.e. whose vertices are either a source or a sink but not both. We show that the retraction problem for a strongly bipartite digraph H has finite duality if and only if H admits a near-unanimity poly...

متن کامل

Hyperspheres Admitting a Pointwise Symmetry Part 1

An affine hypersurface M is said to admit a pointwise symmetry, if there exists a subgroup G of Aut(TpM) for all p ∈ M , which preserves (pointwise) the affine metric h, the difference tensor K and the affine shape operator S. Here, we consider 3-dimensional indefinite affine hyperspheres, i. e. S = HId (and thus S is trivially preserved). First we solve an algebraic problem. We determine the n...

متن کامل

Graphs Admitting (1, ≤ 2)-identifying Codes

A (1,≤ 2)-identifying code is a subset of the vertex set C of a graph such that each pair of vertices intersects C in a distinct way. This has useful applications in locating errors in multiprocessor networks and threat monitoring. At the time of writing, there is no simply-stated rule that will indicate if a graph is (1,≤ 2)-identifiable. As such, we discuss properties that must be satisfied b...

متن کامل

Efficient Reassembling of Graphs, Part 1: The Linear Case

The reassembling of a simple connected graph G = (V,E) is an abstraction of a problem arising in earlier studies of network analysis. Its simplest formulation is in two steps: (1) We cut every edge of G into two halves, thus obtaining a collection of n = ∣V ∣ one-vertex components, such that for every v ∈ V the one-vertex component {v} has ∣degree(v) ∣ half edges attached to it. (2) We splice t...

متن کامل

ذخیره 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: SIAM Journal on Discrete Mathematics

سال: 2013

ISSN: 0895-4801,1095-7146

DOI: 10.1137/120894312