From: Nicolas BERGER <Nicolas.Berger_at_univ-nantes.fr>

Date: Fri, 15 Jun 2007 13:43:00 +0200 (CEST)

Date: Fri, 15 Jun 2007 13:43:00 +0200 (CEST)

> Nicolas BERGER wrote: >> Hi everyone >> >> Is it possible to declare constants i.e. variable that are not reduced ? >> For example, in the following problem, not reducing the domain of D but >> only the domains of X and Y : >> >> [X,Y] $:: [-1.1..0.72], >> D :: [1,4,7], >> X + D #< 3, >> Y + D #< 1. > > Hi Nicolas, > > What exactly do you mean with this? > Maybe you mean that for each value in the domain of D, there exists a > value in the domain of X such that the constraint X+D #< 3 is satisfied. > > If this is the case, you probably need a quantified CSP solver (QCSP). > Have a look at the following *real-life* (robot arm movement) CSP : Tx is 10.0, Ty is 6.0, X0 is 8, Y0 is 4, D $:: [1.99..2.01], A $:: [2.0..8.0], B $:: [2.0..8.0], Alpha $:: [0.. pi], Beta $:: [0.. pi], X $:: [0..Tx], Y $:: [0..Ty], I :: [2..5], J :: [2..5] ; A * sin(Alpha) $= B * sin(Beta - Alpha) + Y, A * cos(Alpha) $= X - (B * cos(Beta - Alpha)), A * cos(Alpha) $=< Tx, X $=< Tx, A * sin(Alpha) $=< Ty, Y $=< Ty, (X - X0)^2 + (Y - Y0)^2 $=< 4, A $= (I - 1) * D, B $= (J - 1) * D. D here is a constant term, it doesn't have to be reduced, it is just some feature of the problem : 1.99 $=< D $=< 2.01. Actually, this problem comes from a C++ constraint solving library (ELISA) where D can be declared as of type "IntervalConstant"... Here what I have first thought of is excluding it from the "locate" var list : locate([A,B,Alpha,Beta,X,Y,I,J], [A,B,Alpha,Beta,X,Y,I,J],1e-6,lin). I suppose it means D is excluded from the search procedure (i.e. won't be splitted) but I don't know if it excludes it from the propagation of domain reductions raised by the constraints... Nicolas.Received on Fri Jun 15 2007 - 12:45:12 CEST

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