Jip J. Dekker
f2a1c4e389
git-subtree-dir: software/mza git-subtree-split: f970a59b177c13ca3dd8aaef8cc6681d83b7e813
27 lines
1.2 KiB
MiniZinc
27 lines
1.2 KiB
MiniZinc
%-----------------------------------------------------------------------------%
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% Reflect an array of comparison values onto a comparison value variable using
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% a lexicographic interpretation of the array. The comparison values are
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% encoded as follows: > | = | < as -1 | 0 | +1.
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% Uses of this constraint are generated by Cadmium transformations that
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% simplify ordering constraints on expressions of complex types.
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%-----------------------------------------------------------------------------%
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predicate comparison_rel_array(array[int] of var -1..1: rels, var -1..1: rel) =
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let { int: l = min(index_set(rels)),
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int: u = max(index_set(rels)),
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array[l-1..u] of var -1..1: r }
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in
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r[l-1] = 0 % initial state (before first array position) is 'equal'
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/\
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forall (i in l..u) (
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% new state: as given array at current position if
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% previous state is 'equal', otherwise previous state
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%
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% r[i] = (if r[i-1] = 0 then rels[i] else r[i-1] endif)
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(r[i-1] = 0 -> r[i] = rels[i])
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/\
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(r[i-1] != 0 -> r[i] = r[i-1])
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)
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/\
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r[u] = rel; % final state (at last array position)
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