Generic shape of multichromatic resonance peaks

Ballistic peaks at quantum resonance

We report studies of the motion of cold atoms in a time-dependent optical potential. The dynamics of our system are that of the quantum kicked rotor, and exhibit a wide variety of phenomena. One purely quantum effect is the quantum resonance, which occurs for well-chosen initial conditions and specific values of the period between kicks. Distinctly nonclassical behavior, such as ballistic growt...

The Doppler peaks from a generic defect

We investigate which of the exotic Doppler peak features found for textures and cosmic strings are generic novelties pertaining to defects. We find that the “out of phase” texture signature is an accident. Generic defects, when they generate a secondary peak structure similar to inflation, apply to it an additive shift. It is not necessary for this shift to be “out of phase”. We also show which...

The multichromatic numbers of some Kneser graphs

The Kneser graph K(m, n) has the n-subsets of {1, 2 . . . . . m} as its vertices, two such vertices being adjacent whenever they are disjoint. The kth multichromatic number of the graph G is the least integer t such that the vertices of G can be assigned k-subsets of {1, 2,... ,t}, so that adjacent vertices of G receive disjoint sets. The values of xk(K(m, n)) are computed for n = 2, 3 and boun...

Generic Shape Learning and Recognition

Generic Shape Classification for Retrieval

We present a shape classification technique for structural content–based retrieval of two-dimensional vector drawings. Our method has two distinguishing features. For one, it relies on explicit hierarchical descriptions of drawing structure by means of spatial relationships and shape characterization. However, unlike other approaches which attempt rigid shape classification, our method relies o...