University of Puerto Rico at Río Piedras

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19922025

most citedThe Arecibo Legacy Fast ALFA Survey: I. Science Goals, Survey Design and Strategy

830 citations

researchers with a paper here

Counting papers with at most 25 authors, so collaboration author lists do not stand in for the people here.

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Showing math.COShow all

14 papers · 1 filter

math.CO2017

Nonexistence of Efficient Dominating Sets in the Cayley Graphs Generated by Transposition Trees of Diameter 3

Italo J. Dejter, Oscar Tomaiconza

Let $d, n$ be positive integers such that $d < n$ , and let $X_{n}^{d}$ be a Cayley graph generated by a transposition tree of diameter $d$ . It is known that every $X_{n}^{d}$ with $d < 3$ split…

math.CO2012

Worst-case efficient dominating sets in digraphs

Italo J. Dejter

Let $1 \leq n \in Z$ . {\it Worst-case efficient dominating sets in digraphs} are conceived so that their presence in certain strong digraphs $S T_{n}$ corresponds to that of effici…

math.CO2011

Orienting and separating distance-transitive graphs

Italo J. Dejter

It is shown that exactly 7 distance-transitive cubic graphs among the existing 12 possess a particular ultrahomogeneous property with respect to oriented cycles realizing the girth…

math.CO2010

A numeral system for the middle-levels graphs

Italo J. Dejter

The middle-levels graph $M_{k}$ ( $0 < k \in Z$ ) has a dihedral quotient pseudograph $R_{k}$ whose vertices are the $k$ -edge ordered trees $T$ , each $T$ encoded as a $(2 k + 1)$ -strin…

math.CO2010

From the Coxeter graph to the Klein graph

Italo J. Dejter

We show that the 56-vertex Klein cubic graph $\G'$ can be obtained from the 28-vertex Coxeter cubic graph $\G$ by 'zipping' adequately the squares of the 24 7-cycles of $\G$ endowe…

math.CO2009

SQS-graphs of Solov'eva-Phelps codes

Italo J. Dejter

A binary extended 1-perfect code $C$ folds over its kernel via the Steiner quadruple systems associated with its codewords. The resulting folding, proposed as a graph inva…

math.CO2009★ 1 cited

Pappus-Desargues digraph confrontation

Italo J. Dejter

Like the Coxeter graph became reattached into the Klein graph in [2], the Levi graphs of the $9_{3}$ and $1 0_{3}$ self-dual configurations, known as the Pappus and Desargues ( $k$ -trans…

math.CO2009★ 1 cited

Quasiperfect domination in triangular lattices

Italo J. Dejter

A vertex subset $S$ of a graph $G$ is a perfect (resp. quasiperfect) dominating set in $G$ if each vertex $v$ of $G ∖ S$ is adjacent to only one vertex ( $d_{v} \in {1, 2}$ vert…

math.CO2009★ 1 cited

SQS-graphs of extended 1-perfect codes

Italo J. Dejter

A binary extended 1-perfect code $C$ folds over its kernel via the Steiner quadruple systems associated with its codewords. The resulting folding, proposed as a graph inva…

math.CO2007★ 28 cited

Perfect domination in rectangular grid graphs

Italo J. Dejter, Abel A. Delgado

A dominating set $S$ in a graph $G$ is said to be perfect if every vertex of $G$ not in $S$ is adjacent to just one vertex of $S$ . Given a vertex subset $S^{'}$ of a side $P_{m}$ of an…

math.CO2007★ 5 cited

Perfect domination in regular grid graphs

Italo J. Dejter

We show there is an uncountable number of parallel total perfect codes in the integer lattice graph $Λ$ of $R^{2}$ . In contrast, there is just one 1-perfect code in $Λ$ and one tota…

math.CO2007

Homogeneous edge-disjoint $K_{2 s}$ and $T_{s t, t}$ unions

Italo J. Dejter

Let $r > 2$ and $σ \in (0, r - 1)$ be integers. We require $t < 2 s$ , where $t = 2^{σ + 1} - 1$ and $s = 2^{r - σ - 1}$ . Generalizing a known ${K_{4}, T_{6, 3}}$ -ultrahomogenous graph $G_{3}^{1}$ , we find tha…

math.CO2007★ 9 cited

On a {K_4,K_{2,2,2}}-ultrahomogeneous graph

Italo J. Dejter

The existence of a connected 12-regular ${K_{4}, K_{2, 2, 2}}$ -ultrahomogeneous graph $G$ is established, (i.e. each isomorphism between two copies of $K_{4}$ or $K_{2, 2, 2}$ in $G$ exte…

math.CO2001★ 1 cited

Structure of Binary Sequences

J. Tharrats

The distribution of a given sequence in the set of all sequences with n ones and m = M - n zeros are found by relating the problem to the partitions of a natural number in m natura…

Nonexistence of Efficient Dominating Sets in the Cayley Graphs Generated by Transposition Trees of Diameter 3

Worst-case efficient dominating sets in digraphs

Orienting and separating distance-transitive graphs

A numeral system for the middle-levels graphs

From the Coxeter graph to the Klein graph

SQS-graphs of Solov'eva-Phelps codes

Pappus-Desargues digraph confrontation

Quasiperfect domination in triangular lattices

SQS-graphs of extended 1-perfect codes

Perfect domination in rectangular grid graphs

Perfect domination in regular grid graphs

Homogeneous edge-disjoint K2s​ and Tst,t​ unions

On a {K_4,K_{2,2,2}}-ultrahomogeneous graph

Structure of Binary Sequences

Homogeneous edge-disjoint $K_{2 s}$ and $T_{s t, t}$ unions