A new two-variable generalization of the chromatic polynomial.
A note on a conjecture of Duval and sturmian words
We prove a long standing conjecture of Duval in the special case of sturmian words.
A Note on a Conjecture of Duval and Sturmian Words
We prove a long standing conjecture of Duval in the special case of Sturmian words.
A note on antichains of words.
A note on complexity of algorithmic nets without cycles
A note on constructing infinite binary words with polynomial subword complexity
Most of the constructions of infinite words having polynomial subword complexity are quite complicated, e.g., sequences of Toeplitz, sequences defined by billiards in the cube, etc. In this paper, we describe a simple method for constructing infinite words w over a binary alphabet { a,b } with polynomial subword complexity pw. Assuming w contains an infinite number of a’s, our method is based on the gap function which gives the distances between consecutive b’s. It is known that if the gap function...
A note on domination in bipartite graphs
DOMINATING SET remains NP-complete even when instances are restricted to bipartite graphs, however, in this case VERTEX COVER is solvable in polynomial time. Consequences to VECTOR DOMINATING SET as a generalization of both are discussed.
A note on domino shuffling.
A note on outerplanarity of product graphs
A note on rectilinearity and angular resolution.
A note on the asymptotic behavior of the heights in -trees for large.
A note on the computational complexity of computing the edge rotation distance between graphs
A note on the hardness results for the labeled perfect matching problems in bipartite graphs
In this note, we strengthen the inapproximation bound of O(logn) for the labeled perfect matching problem established in J. Monnot, The Labeled perfect matching in bipartite graphs, Information Processing Letters96 (2005) 81–88, using a self improving operation in some hard instances. It is interesting to note that this self improving operation does not work for all instances. Moreover, based on this approach we deduce that the problem does not admit constant approximation algorithms for connected...
A note on the number of squares in a partial word with one hole
A well known result of Fraenkel and Simpson states that the number of distinct squares in a word of length n is bounded by 2n since at each position there are at most two distinct squares whose last occurrence starts. In this paper, we investigate squares in partial words with one hole, or sequences over a finite alphabet that have a “do not know” symbol or “hole”. A square in a partial word over a given alphabet has the form uv where u is compatible with v, and consequently, such square is...
A note on tree realizations of matrices
It is well known that each tree metric M has a unique realization as a tree, and that this realization minimizes the total length of the edges among all other realizations of M. We extend this result to the class of symmetric matrices M with zero diagonal, positive entries, and such that mij + mkl ≤ max{mik + mjl, mil + mjk} for all distinct i,j,k,l.
A note on univoque self-sturmian numbers
We compare two sets of (infinite) binary sequences whose suffixes satisfy extremal conditions: one occurs when studying iterations of unimodal continuous maps from the unit interval into itself, but it also characterizes univoque real numbers; the other is a disguised version of the set of characteristic sturmian sequences. As a corollary to our study we obtain that a real number in is univoque and self-sturmian if and only if the -expansion of is of the form , where is a characteristic...
A note on univoque self-Sturmian numbers
We compare two sets of (infinite) binary sequences whose suffixes satisfy extremal conditions: one occurs when studying iterations of unimodal continuous maps from the unit interval into itself, but it also characterizes univoque real numbers; the other is a disguised version of the set of characteristic Sturmian sequences. As a corollary to our study we obtain that a real number β in (1,2) is univoque and self-Sturmian if and only if the β-expansion of 1 is of the form 1v, where v is a characteristic...
A novel approach for detection and elimination of automorphic graphs in graph databases.
A one-sided Zimin construction.
A partially persistent data structure for the set-union problem