arXiv subjects

Yadira Torres-Nuñez

Publications and source records attributed to Yadira Torres-Nuñez.

3 recordsLinked to original sources

arXiv2020

Distinguishing wheel graphs by the alliance polynomial

Distinctive power of the alliance polynomial has been studied in previous works, for instance, it has been proved that the empty, path, cycle, complete, complete without one edge and star graphs are characterized by its alliance polynomial. Moreover, it has been proved that the family of alliance polynomial of regular graphs with small degree is a very special one, since it does not contain alliance polynomial of graphs other than regular graph with the same degree. In this work we prove that the alliance polynomial also determines the wheel graphs.

math.CO↗

arXiv2015

Alliance polynomial of regular graphs

The alliance polynomial of a graph $G$ with order $n$ and maximum degree $Δ$ is the polynomial $A(G; x) = \sum_{k=-Δ}^Δ A_{k}(G) \, x^{n+k}$, where $A_{k}(G)$ is the number of exact defensive $k$-alliances in $G$. We obtain some properties of $A(G; x)$ and its coefficients for regular graphs. In particular, we characterize the degree of regular graphs by the number of non-zero coefficients of their alliance polynomial. Besides, we prove that the family of alliance polynomials of $Δ$-regular graphs with small degree is a very special one, since it does not contain alliance polynomials of graphs which are not $Δ$-regular. By using this last result and direct computation we find that the alliance polynomial determines uniquely each cubic graph of order less than or equal to $10$.

math.CO↗

arXiv2014

Computing the alliance polynomial of a graph

The alliance polynomial of a graph $Γ$ with order $n$ and maximum degree $δ_1$ is the polynomial $A(Γ; x) = \sum_{k=-δ_1}^{δ_1} A_{k}(Γ) \, x^{n+k}$, where $A_{k}(Γ)$ is the number of exact defensive $k$-alliances in $Γ$. We provide an algorithm for computing the alliance polynomial. Furthermore, we obtain some properties of $A(Γ; x)$ and its coefficients. In particular, we prove that the path, cycle, complete and star graphs are characterized by their alliance polynomials. We also show that the alliance polynomial characterizes many graphs that are not distinguished by other usual polynomials of graphs.

math.CO↗