Note on PI and Szeged indices

In theoretical chemistry molecular structure descriptors are used for modeling physico-chemical, pharmacological, toxicologic, biological and other properties of chemical compounds. In this paper we study distance-based graph invariants and present some improved and corrected sharp inequalities for PI, vertex PI, Szeged and edge Szeged topological indices, involving the number of vertices and edges, the diameter, the number of triangles and the Zagreb indices. In addition, we give a complete characterization of the extremal graphs.Comment: 10 pages, 3 figure

A De Bruijn–Erdős theorem for chordal graphs

International audienceA special case of a combinatorial theorem of De Bruijn and Erd˝ os asserts that every noncollinear set of n points in the plane determines at least n distinct lines. Chen and Chvátal suggested a possible generalization of this assertion in metric spaces with appropriately defined lines. We prove this generalization in all metric spaces induced by connected chordal graphs

Probabilistic reasoning with a bayesian DNA device based on strand displacement

We present a computing model based on the DNA strand displacement technique which performs Bayesian inference. The model will take single stranded DNA as input data, representing the presence or absence of a specific molecular signal (evidence). The program logic encodes the prior probability of a disease and the conditional probability of a signal given the disease playing with a set of different DNA complexes and their ratios. When the input and program molecules interact, they release a different pair of single stranded DNA species whose relative proportion represents the application of Bayes? Law: the conditional probability of the disease given the signal. The models presented in this paper can empower the application of probabilistic reasoning in genetic diagnosis in vitro

Intersperse Coloring

the thesis, including any required final revisions, as accepted by my examiners. I understand that my thesis may be made electronically available to the public. In this thesis, we introduce the intersperse coloring problem, which is a generalized version of the hypergraph coloring problem. In the intersperse coloring problem, we seek a coloring that assigns at least ℓ different colors to each hyperedge of the input hypergraph, where ℓ is an input parameter of the problem. We show that the notion of intersperse coloring unifies several well-known coloring problems, in addition to the conventional graph and hypergraph coloring problems, such as the strong coloring of hypergraphs, the star coloring problem, the problem of proper coloring of graph powers, the acyclic coloring problem, and the frugal coloring problem. We also provide a number of upper and lower bounds on the intersperse coloring problem on hypergraphs in the general case. The nice thing about our general bounds is that they can be applied to all the coloring problems that are specia