Exact Algorithms for Graph Homomorphisms
نویسندگان
چکیده
منابع مشابه
A Hybrid Graph Representation for Exact Graph Algorithms
Many exact search algorithms for NP-hard graph problems adopt the old Davis-Putman branch-and-reduce paradigm. The performance of these algorithms often suffers from the increasing number of graph modifications, such as vertex/edge deletions, that reduce the problem instance and have to be “taken back” frequently during the search process. We investigate practical implementation-based aspects o...
متن کاملGraph Homomorphisms for Quantum Players
A homomorphism from a graph X to a graph Y is an adjacency preserving mapping f : V (X)→ V (Y ). We consider a nonlocal game in which Alice and Bob are trying to convince a verifier with certainty that a graph X admits a homomorphism to Y . This is a generalization of the well-studied graph coloring game. Via systematic study of quantum homomorphisms we prove new results for graph coloring. Mos...
متن کاملGraph Powers and Graph Homomorphisms
In this paper we investigate some basic properties of fractional powers. In this regard, we show that for any rational number 1 ≤ 2r+1 2s+1 < og(G), G 2r+1 2s+1 −→ H if and only if G −→ H− 2s+1 2r+1 . Also, for two rational numbers 2r+1 2s+1 < 2p+1 2q+1 and a non-bipartite graph G, we show that G 2r+1 2s+1 < G 2p+1 2q+1 . In the sequel, we introduce an equivalent definition for circular chromat...
متن کاملCounting Graph Homomorphisms
3 Connection matrices 9 3.1 The connection matrix of a graph parameter . . . . . . . . . . . . . . . . . . . . 9 3.2 The rank of connection matrices . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 3.3 Connection matrices of homomorphisms . . . . . . . . . . . . . . . . . . . . . . . 12 3.4 The exact rank of connection matrices for homomorphisms . . . . . . . . . . . . 13 3.5 Extensions...
متن کاملGraph homomorphisms III: Models
Following the last talk on graph homomorphisms, we continue to discuss some examples of graph homomorphisms. But this time we will focus on some models, that is, the homomorphism G → H for the graph H with fixed weights. The main reference is Section 1 in [2].
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: Theory of Computing Systems
سال: 2007
ISSN: 1432-4350,1433-0490
DOI: 10.1007/s00224-007-2007-x