Sagnik Sen

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The abelian sandpile models feature a finite abelian group G generated by the operators corresponding to particle addition at various sites. We study the canonical decomposition of G as a product of cyclic groups G = Z d1 × Z d2 × Z d3 · · · × Z dg where g is the least number of generators of G, and d i is a multiple of d i+1. The structure of G is(More)
We define and study a class of graphs, called 2-stab interval graphs (2SIG), with boxicity 2 which properly contains the class of interval graphs. A 2SIG is an axes-parallel rectangle intersection graph where the rectangles have unit height (that is, length of the side parallel to Y-axis) and intersects either of the two fixed lines, parallel to the X-axis,(More)
The clique number of an undirected graph G is the maximum order of a complete subgraph of G and is a well-known lower bound for the chromatic number of G. Every proper k-coloring of G may be viewed as a homomorphism (an edge-preserving vertex mapping) of G to the complete graph of order k. By considering homomorphisms of oriented graphs (digraphs without(More)
The first and second homology groups, H 1 and H 2 , are computed for configuration spaces of framed three-dimensional point-particles with annihilation included , when up to two particles and an antiparticle are present, the types of frames considered being S 2 and SO(3). Whereas a recent calculation for two-dimensional particles used the Mayer-Vietoris(More)