38 research outputs found
On a Vizing-type integer domination conjecture
Given a simple graph , a dominating set in is a set of vertices
such that every vertex not in has a neighbor in . Denote the domination
number, which is the size of any minimum dominating set of , by .
For any integer , a function
is called a \emph{-dominating function} if the sum of its function
values over any closed neighborhood is at least . The weight of a
-dominating function is the sum of its values over all the vertices. The
-domination number of , , is defined to be the
minimum weight taken over all -domination functions. Bre\v{s}ar,
Henning, and Klav\v{z}ar (On integer domination in graphs and Vizing-like
problems. \emph{Taiwanese J. Math.} {10(5)} (2006) pp. 1317--1328) asked
whether there exists an integer so that . In this note we use the Roman -domination number,
of Chellali, Haynes, Hedetniemi, and McRae, (Roman
-domination. \emph{Discrete Applied Mathematics} {204} (2016) pp.
22-28.) to prove that if is a claw-free graph and is an arbitrary
graph, then , which also implies the conjecture for all .Comment: 8 page
Advancements in Research Mathematics through AI: A Framework for Conjecturing
This paper introduces a general framework for computer-based conjecture
generation, particularly those conjectures that mathematicians might deem
substantial and elegant. We describe our approach and demonstrate its
effectiveness by providing examples of its application in producing publishable
research and unexpected mathematical insights. We anticipate that our
discussion of computer-assisted mathematical conjecturing will catalyze further
research into this area and encourage the development of more advanced
techniques than the ones presented herein
Upper bounds on the k-forcing number of a graph
Given a simple undirected graph and a positive integer , the
-forcing number of , denoted , is the minimum number of vertices
that need to be initially colored so that all vertices eventually become
colored during the discrete dynamical process described by the following rule.
Starting from an initial set of colored vertices and stopping when all vertices
are colored: if a colored vertex has at most non-colored neighbors, then
each of its non-colored neighbors becomes colored. When , this is
equivalent to the zero forcing number, usually denoted with , a recently
introduced invariant that gives an upper bound on the maximum nullity of a
graph. In this paper, we give several upper bounds on the -forcing number.
Notable among these, we show that if is a graph with order and
maximum degree , then . This simplifies to, for the zero forcing number case
of , . Moreover, when and the graph is -connected, we prove that , which is an improvement when , and
specializes to, for the zero forcing number case, . These results resolve a problem posed by
Meyer about regular bipartite circulant graphs. Finally, we present a
relationship between the -forcing number and the connected -domination
number. As a corollary, we find that the sum of the zero forcing number and
connected domination number is at most the order for connected graphs.Comment: 15 pages, 0 figure