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laws: (==) iff they are relabellings of each other

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hi 2025-08-16 08:58:22 +00:00
parent b0e98b0e51
commit 550e589bc8
2 changed files with 12 additions and 3 deletions
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9
lib/Logic/Statement.hs
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@ -28,3 +28,12 @@ substatements s@(And s1 s2) = (s:) $ substatements s1 ++ substatements s2
substatements s@(Or s1 s2) = (s:) $ substatements s1 ++ substatements s2
substatements s@(Implies s1 s2) = (s:) $ substatements s1 ++ substatements s2
substatements s@(Iff s1 s2) = (s:) $ substatements s1 ++ substatements s2
relabellings :: Statement -> Statement -> Bool
relabellings (Atom _) (Atom _) = True
relabellings (Not s1) (Not r1) = relabellings s1 r1
relabellings (And s1 s2) (And r1 r2) = relabellings s1 r1 && relabellings s2 r2
relabellings (Or s1 s2) (Or r1 r2) = relabellings s1 r1 && relabellings s2 r2
relabellings (Implies s1 s2) (Implies r1 r2) = relabellings s1 r1 && relabellings s2 r2
relabellings (Iff s1 s2) (Iff r1 r2) = relabellings s1 r1 && relabellings s2 r2
relabellings _ _ = False

6
lib/Logic/Statement/Laws.hs
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@ -1,7 +1,7 @@
module Logic.Statement.Laws where
import Logic.Parse (eof, mkInput)
import Logic.Statement (Statement(..))
import Logic.Statement (Statement(..), relabellings)
import Logic.Statement.Parse (stmt)
import Logic.Statement.Serialize (serialize, SerializeFormat(Plain))
import Logic.Graph (bfs, verifyPath, VerifyPathError)
@ -20,8 +20,8 @@ data Law = Law
instance Eq Law where
law1 == law2 =
lawLhs law1 == lawLhs law2
&& lawRhs law1 == lawRhs law2
relabellings (lawLhs law1) (lawLhs law2)
&& relabellings (lawRhs law1) (lawRhs law2)
instance Show Law where
show law =