Constraint

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trmonc4t boricnoc If you are doing constrained optimization with DynaMITE, your program should specify what the constraints are. You should assert or derive items of the form

constrain(item==value)

or

constrain(item >= value)

For example, suppose you have written a probabilistic CKY parser. You want to require that all the rewrite rules with a given left-hand side sum to one. So you write

sum_lhs(Lhs) += rewrite(Lhs,_).              % unary rewrite rule
sum_lhs(Lhs) += rewrite(Lhs,_,_).            % binary rewrite rule
constrain(sum_lhs(Lhs)==1) |= ?sum_lhs(Lhs). % we constrain sum_lhs(np) if it was derived,
                                             % i.e., if there were any rules with np as lhs

If your rewrite rule probabilities are in the logarithmic domain, you would write

logsum_lhs(Lhs) log+= rewrite(Lhs,_).       
logsum_lhs(Lhs) log+= rewrite(Lhs,_,_).     
constrain(logsum_lhs(Lhs)==0) |= ?sum_lhs(Lhs).

Of course, a given version of DynaMITE can only handle certain kinds of constraints. The current version can handle sum-to-one constraints in the log domain, as shown above.

At the moment, DynaMITE expects a slightly different form: constrain_eq(item,value). Also at the moment, you need to explicitly declare :- oldquery(constraints, constrain_eq(_,_)). This will become unnecessary in future (and perhaps even invalid, since oldquery is deprecated).
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