Expr: Canonicalize transformations #929
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On expression level, we convert all inequalities to use (signed) less-than operator, (S)LT. On propositional level, we express inequalities using PLT and PLEq. Here, it might be beneficial to keep leq-or-equal operator, so as to express as much as possible with positive atoms, avoiding negation. We also take advantage of "bool-like" expressions, i.e., word-expressions that we can express on the propositional level. These include "IsZero", "(S)LT", "Eq". The result of these operations can only be 0 or 1, so we can simplify a propositon (PEq (Lit 0) e) where e is bool-like (and also if it is equal to Lit 1).
msooseth
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Nov 15, 2025
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Thanks! LGTM!
I probably should have added some example Props that the old set simplified, and checked that it got smaller. I think there were some contracts that could be significantly simplified with the right rules. We are currently not tracking if we accidentally don't simplify something with a change. Next time I look at some Props, I'll add some tests for the size of the simplified Prop.
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We should definitely gather more unit tests for simplifications! |
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Description
On expression level, we convert all inequalities to use (signed) less-than operator, (S)LT.
On propositional level, we express inequalities using PLT and PLEq. Here, it might be beneficial to keep leq-or-equal operator, so as to express as much as possible with positive atoms, avoiding negation.
We also take advantage of "bool-like" expressions, i.e., word-expressions that we can express on the propositional level. These include "IsZero", "(S)LT", "Eq".
The result of these operations can only be 0 or 1, so we can simplify a propositon (PEq (Lit 0) e) where e is bool-like (and also if it is equal to Lit 1).
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