Propagating N-ary rigid-body constraints

The, paper presents an algorithm to propagate an n-ary constraint (with n greater than 2) specifying the relative positions of points in a three-dimensional rigid group. The variables to restrict are the positions (x, y, and z coordinates) of the points, and we assume the variable domains are cuboids, with the faces orthogonal to the coordinate axes. This algorithm is part of PSICO (Processing Structural Information with Constraint programming and Optimisation), a method we are developing to integrate experimental and theoretical data to solve protein structures [1,2]. We also present some preliminary results, and explain how this algorithm can be used to combine theoretical information such as secondary structure prediction or homology modelling with Nuclear Magnetic Resonance (NMR) data.