Mark G. Alford, Krishna Rajagopal, Sanjay Reddy, and Andrew W. Steiner Department of Physics, Washington University, St Louis, MO 63130, USA Center for Theoretical Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA Nuclear Science Division, MS 70R319, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA Theoretical Division, Los Alamos National Laboratory, Los Al...

Recently, Hua et al. defined a new topological index based on degrees and inverse of distances between all pairs of vertices. They named this new graph invariant as reciprocal degree distance as 1 { , } ( ) ( ( ) ( ))[ ( , )] RDD(G) = u v V G d u  d v d u v , where the d(u,v) denotes the distance between vertices u and v. In this paper, we compute this topological index for Grassmann graphs.

Two graphs G and H are hypomorphic if there exists a bijection φ : V (G)→ V (H) such that G− v ∼= H − φ(v) for each v ∈ V (G). A graph G is reconstructible if H ∼= G for all H hypomorphic to G. It is well known that not all infinite graphs are reconstructible. However, the Harary-Schwenk-Scott Conjecture from 1972 suggests that all locally finite trees are reconstructible. In this paper, we con...

A graph is said to be a sum graph if there exists a set S of positive integers as its node set, with two nodes adjacent whenever their sum is in S. An integral sum graph is defined just as the sum graph, the difference being that S is a subset of 2~ instead of N*. The sum number of a given graph G is defined as the smallest number of isolated nodes which when added to G result in a sum graph. T...

A Steiner triple system of order v, denoted STS (v), is a pair (V, B); V is a u-set of elements and B is a collection of 3-subsets of V called blocks. Each unordered pair of elements is contained in precisely one block. There is a substantial body of research on STS, partially because of their wide applicability in the design of experiments, and in the theory of error-correcting codes. In the d...

In this paper, we study the interconnect layout optimization problem under a higher-order RLC model to optimize not only delay, but also waveform, for interconnects with non-monotone signal response in the context of MCM global routing. We propose a unified approach that considers topology optimization and waveform optimization simultaneously. Using a new incremental moment computation algorith...

We complete the determination of the chromatic number of 6valent circulants of the form C(n; a, b, a+b) and show how this can be applied to improving the upper bound on the chromatic index of cyclic Steiner triple systems.

In this paper, we reduce Prize-Collecting Steiner TSP (PCTSP), Prize-Collecting Stroll (PCS), Prize-Collecting Steiner Tree (PCST), Prize-Collecting Steiner Forest (PCSF) and more generally Submodular Prize-Collecting Steiner Forest (SPCSF) on planar graphs (and more generally bounded-genus graphs) to the same problems on graphs of bounded treewidth. More precisely, we show any α-approximation ...

In the early 60s, Harary and Hill conjectured H(n) := 1 4b2 cbn−1 2 cbn−2 2 cbn−3 2 c to be the minimum number of crossings among all drawings of the complete graph Kn. It has recently been shown that this conjecture holds for so-called shellable drawings of Kn. For n ≥ 11 odd, we construct a non-shellable family of drawings of Kn with exactly H(n) crossings. In particular, every edge in our dr...

Given a set P of points (clients) in the plane, a Euclidean 2-centre of P is a set of two points (facilities) in the plane such that the maximum distance from any client to its nearest facility is minimized. Geometrically, a Euclidean 2-centre of P corresponds to a cover of P by two discs of minimum radius r (the Euclidean 2-radius). Given a set of mobile clients, where each client follows a co...