Refactored and cleaned up some things

app/Main.hs

@@ -8,8 +8,8 @@ import DotWriter
 import Mealy
 import MealyRefine
 import Merger
-import Partition
-import Preorder
+import Data.Partition
+import Data.Preorder
 
 import Control.Monad (forM_)
 import Data.Bifunctor
@@ -84,8 +84,7 @@ main = do
 
   -- First we check for equivalent partitions, so that we skip redundant work.
   let
-    preord p1 p2 = toPreorder (comparePartitions p1 p2)
-    (equiv, uniqPartitions) = equivalenceClasses preord projections
+    (equiv, uniqPartitions) = equivalenceClasses comparePartitions projections
 
   putStrLn ""
   putStrLn "Representatives"
@@ -102,7 +101,7 @@ main = do
   -- Then we compare each pair of partitions. We only keep the finest
   -- partitions, since the coarse ones don't provide value to us.
   let
-    (topMods, downSets) = maximalElements preord uniqPartitions
+    (topMods, downSets) = maximalElements comparePartitions uniqPartitions
     foo (a, b) = (numBlocks b, a)
 
   putStrLn ""
@@ -144,7 +143,7 @@ main = do
         let
           filename = "partition_" <> show componentIdx <> ".dot"
           idx2State = Map.map head . converseRelation $ state2idx
-          stateBlocks = fmap (fmap (idx2State Map.!)) . Partition.toBlocks $ partition
+          stateBlocks = fmap (fmap (idx2State Map.!)) . toBlocks $ partition
           content = unlines . fmap unwords $ stateBlocks
 
         putStrLn $ "Output (partition) in file " <> filename

app/Playground.hs

@@ -1,17 +1,20 @@
 module Main where
 
-import Bisimulation (bisimulation2, empty, equate, equivalent)
+import Bisimulation (bisimulation2)
+import Data.UnionFind
 import DotParser (convertToMealy, parseTransFull)
 import Mealy (MealyMachine (..), outputFunction, transitionFunction)
-import SplittingTree (PRState (..), initialPRState, refine)
+import Data.Partition (numBlocks)
+import SplittingTree (PRState (..), getPartition, initialPRState, refine)
 import StateIdentifiers (stateIdentifierFor)
-import Trie qualified
+import Data.Trie qualified as Trie
 
 import Control.Monad.Trans.State (execStateT)
 import Data.List qualified as List
 import Data.Map.Strict qualified as Map
 import Data.Maybe (isJust, mapMaybe)
 import Data.Set qualified as Set
+import MealyRefine
 import System.Environment (getArgs)
 import Text.Megaparsec (parseMaybe)
 
@@ -21,7 +24,8 @@ main = do
   case args of
     ("HSI" : ls) -> mainHSI ls
     ("InputDecomp" : ls) -> mainInputDecomp ls
-    _ -> putStrLn "Please provide one of [HSI, InputDecomp]"
+    ("Refine" : ls) -> mainRefine ls
+    _ -> putStrLn "Please provide one of [HSI, InputDecomp, Refine]"
 
 mainHSI :: [String] -> IO ()
 mainHSI args = case args of
@@ -87,9 +91,14 @@ mainInputDecomp args = case args of
         composition i j = interleavingComposition [i] [j] model
         bisim i j =
           let compo = composition i j
-           in bisimulation2 [i, j]
-                (outputFunction model) (transitionFunction model) (initialState model)
-                (outputFunction compo) (transitionFunction compo) (initialState compo)
+           in bisimulation2
+                [i, j]
+                (outputFunction model)
+                (transitionFunction model)
+                (initialState model)
+                (outputFunction compo)
+                (transitionFunction compo)
+                (initialState compo)
         dependent i j = isJust $ bisim i j
         dependentPairs = [(i, j) | i <- inputs model, j <- inputs model, j > i, dependent i j]
 
@@ -118,3 +127,29 @@ mainInputDecomp args = case args of
       0 -> putStrLn "ERROR"
       1 -> putStrLn "INDECOMPOSABLE"
       n -> putStrLn ("MAYBE DECOMPOSABLE: " ++ show n ++ " classes")
+
+-- Used to determine whether Copar is faster than SplittingTree (it is).
+mainRefine :: [String] -> IO ()
+mainRefine args = case args of
+  [dotFile, copar] -> run dotFile (read copar)
+  _ -> putStrLn "Please provide a dot file and Boolean"
+ where
+  run dotFile copar = do
+    m <- convertToMealy . mapMaybe (parseMaybe parseTransFull) . lines <$> readFile dotFile
+    putStrLn $ "file parsed, initial state = " <> initialState m
+    if copar
+      then runCopar m
+      else runSplittingTree m
+
+  runCopar m =
+    let printPartition p = putStrLn $ "Done " <> show (numBlocks p)
+     in printPartition (refineMealy (mealyMachineToEncoding m))
+
+  runSplittingTree MealyMachine{..} = do
+    let
+      outputFuns = [(i, fun) | i <- inputs, let fun s = fst (behaviour s i)]
+      reverseTransitionMaps i = Map.fromListWith (++) [(t, [s]) | s <- states, let t = snd (behaviour s i)]
+      reverseFuns = [(i, fun) | i <- inputs, let mm = reverseTransitionMaps i, let fun s = Map.findWithDefault [] s mm]
+
+    PRState{..} <- execStateT (refine (\_ -> pure ()) outputFuns reverseFuns) (initialPRState states)
+    putStrLn $ "Done" <> show (Map.size (getPartition partition))

fourmolu.yaml

@@ -0,0 +1,5 @@
+indentation: 2
+haddock-style: single-line
+single-constraint-parens: auto
+single-deriving-parens: auto
+respectful: true

mealy-decompose.cabal

@@ -12,7 +12,6 @@ common stuff
   build-depends:
     base ^>=4.19.0.0,
     containers,
-    copar,
     data-ordlist,
     megaparsec,
     transformers
@@ -25,18 +24,20 @@ library
   hs-source-dirs: src
   exposed-modules:
     Bisimulation,
+    Data.Partition,
+    Data.Preorder,
+    Data.Trie,
+    Data.UnionFind,
     DotParser,
     DotWriter,
     LStar,
     Mealy,
     MealyRefine,
     Merger,
-    Partition,
-    Preorder,
     SplittingTree,
-    StateIdentifiers,
-    Trie
+    StateIdentifiers
   build-depends:
+    copar,
     vector
 
 executable mealy-decompose

other/decompose_fsm_optimise.py

@@ -137,10 +137,6 @@ def print_table(cell, rs, cs):
     print('')
 
 
-def print_eqrel(rel, xs):
-  print_table(lambda r, c: 'Y' if rel(r, c) else '·', xs, xs)
-
-
 class Progress:
   def __init__(self, name: str, guess: int):
     self.reset(name, guess, show=False)

src/Bisimulation.hs

@@ -1,37 +1,9 @@
 module Bisimulation where
 
+import Data.UnionFind (empty, equivalent, equate)
 import Data.List (find)
-import Data.Map.Strict qualified as Map
 import Data.Sequence qualified as Seq
 
--- Dit is niet de echte union-find datastructuur (niet erg efficient),
--- maar wel simpel en beter dan niks.
-newtype UnionFind x = MkUnionFind {unUnionFind :: Map.Map x x}
-
--- Alle elementen zijn hun eigen klasse, dit geven we aan met Nothing.
-empty :: UnionFind x
-empty = MkUnionFind Map.empty
-
--- Omdat we een pure interface hebben, doen we hier geen path-compression.
-equivalent :: Ord x => x -> x -> UnionFind x -> Bool
-equivalent x y (MkUnionFind m) = root x == root y
- where
-  root z = maybe z root (Map.lookup z m)
-
--- Hier kunnen we wel path-compression doen. We zouden ook nog een rank
--- optimalisatie kunnen (moeten?) doen. Maar dan moeten we meer onthouden.
-equate :: Ord x => x -> x -> UnionFind x -> UnionFind x
-equate x y (MkUnionFind m1) =
-  let (rx, m2) = rootCP x m1 rx
-      (ry, m3) = rootCP y m2 ry
-   in if rx == ry
-        then MkUnionFind m3
-        else MkUnionFind (Map.insert rx ry m3)
- where
-  rootCP z m r = case Map.lookup z m of
-    Nothing -> (z, m)
-    Just w -> Map.insert z r <$> rootCP w m r
-
 -- Bisimulatie in 1 machine
 bisimulation :: (Eq o, Ord s) => [i] -> (s -> i -> o) -> (s -> i -> s) -> s -> s -> Maybe [i]
 bisimulation alphabet output transition x y = go (Seq.singleton ([], x, y)) empty

src/Data/Partition.hs

@@ -0,0 +1,85 @@
+{-# LANGUAGE PackageImports #-}
+
+module Data.Partition (
+  -- $partitions
+  module Data.Partition,
+) where
+
+import Data.Preorder
+
+import Control.Monad.Trans.State.Strict (get, put, runState)
+import Data.Coerce (coerce)
+import Data.Map.Strict qualified as Map
+import Data.Partition.Common (Block (..))
+import Data.Vector qualified as V
+import "copar" Data.Partition (Partition (..), blockOfState, numStates, toBlocks)
+
+-- $partitions
+--
+-- This module re-exports the `Data.Partition` module from the `copar` library,
+-- and adds some additional functions for working with partitions. A partition
+-- on a set of type @a@ is represented as a map @a -> `Block`@, where a `Block`
+-- is a unique identifier (integer) for a set of elements.
+--
+-- In this module, we define
+--
+-- * `commonRefinement` to compute the common refinement of two partitions.
+-- * `isRefinementOf2` to check if one partition is a refinement of another.
+-- * `isEquivalent` to check if two partitions are equal.
+-- * `comparePartitions` to compare two partitions in the partition lattice.
+--
+-- Partitions form a lattice (the so-called /partition lattice/), where the
+-- partial order is given by the refinement relation. We put the finest
+-- partition at the top, and the coarsest at the bottom. (This is the opposite
+-- of the convection used on wikipedia.)
+
+-- | Returns the common refinement of two partitions. This is the coarsest
+-- partition which is finer than either input, i.e., the lowest upper bound.
+commonRefinement :: Partition -> Partition -> Partition
+commonRefinement p1 p2 =
+  let n = numStates p1
+      sa1 = (stateAssignment p1 V.!)
+      sa2 = (stateAssignment p2 V.!)
+      blockAtIdx i = do
+        (m, b) <- get
+        let key = (sa1 i, sa2 i)
+        case Map.lookup key m of
+          Just b0 -> return b0
+          Nothing -> do
+            put (Map.insert key b m, succ b)
+            return b
+      (vect, (_, nextBlock)) = runState (V.generateM n blockAtIdx) (Map.empty, 0)
+   in Partition{numBlocks = coerce nextBlock, stateAssignment = vect}
+
+-- | This function checks whether one partition is a refinement of the other.
+-- This function already appears in the `copar` library, but the one here is
+-- faster. This function is the same as `>=` in the partition lattice.
+
+-- Could be made faster by doing what commonRefinement is doing but
+-- stopping early. But it's fast enough for now, so I won't bother.
+isRefinementOf2 :: Partition -> Partition -> Bool
+isRefinementOf2 refined original = comparePartitions refined original == GT'
+
+-- | Checks whether two partitions are equal as partitions. Note that the `Eq`
+-- instance on partitions checks for equality of the state assignments, not
+-- whether the partitions are equal as partitions.
+isEquivalent :: Partition -> Partition -> Bool
+isEquivalent p1 p2 = comparePartitions p1 p2 == EQ'
+
+-- | Compares two partitions. Returns `EQ'` if the partitions are equal, `GT'`
+-- if the first partition is a refinement of the second, `LT'` if the first
+-- partition is a coarsening of the second, and `IC'` if the partitions are
+-- incomparable.
+comparePartitions :: Partition -> Partition -> PartialOrdering
+comparePartitions p1 p2
+  | p1 == p2 = EQ'
+  | otherwise =
+      let glb = commonRefinement p1 p2
+          n1 = numBlocks p1
+          n2 = numBlocks p2
+          n3 = numBlocks glb
+       in case (n1 == n3, n2 == n3) of
+            (True, True) -> EQ'
+            (True, False) -> GT'
+            (False, True) -> LT'
+            (False, False) -> IC'

src/Data/Preorder.hs

@@ -1,14 +1,6 @@
 {-# LANGUAGE PatternSynonyms #-}
 
-module Preorder where
-
--- \|
--- This modules includes some algorithms to deal with preorders. For our use-case
--- it could be done efficiently with a single function. But this makes it a bit
--- unwieldy. So I have separated it into two functions:
--- 1. One function takes a preorder and computes the equivalence classes.
--- 2. The second function takes the order into account (now only on the
---    representatives of the first function) and returns the "top" elements.
+module Data.Preorder where
 
 import Control.Monad.Trans.Writer.Lazy (runWriter, tell)
 import Data.Bifunctor
@@ -16,18 +8,30 @@ import Data.Foldable (find)
 import Data.Map.Strict qualified as Map
 import Data.Set qualified as Set
 
+-- * Basic types
+
+-- $moduleDocs
+-- This modules includes some algorithms to deal with preorders. For our
+-- use-case it could be done efficiently with a single function. But this makes
+-- it a bit unwieldy. So I have separated it into two functions:
+--
+-- 1. One function takes a preorder and computes the equivalence classes.
+-- 2. The second function takes the order into account (now only on the
+--    representatives of the first function) and returns the "top" elements.
+
+-- | The partial order adds one constructor to the `Ordering` data type: the
+-- possibility of elements being incomparable.
 type PartialOrdering = Maybe Ordering
 
 pattern EQ', LT', GT', IC' :: PartialOrdering
 pattern EQ' = Just EQ
--- \^ Equivalent (or equal)
+-- ^ Equivalent (or equal)
 pattern LT' = Just LT
--- \^ Strictly less than
+-- ^ Strictly less than
 pattern GT' = Just GT
--- \^ Strictly greater than
+-- ^ Strictly greater than
 pattern IC' = Nothing
-
--- \^ Incomparable
+-- ^ Incomparable
 
 -- | A preorder should satisfy reflexivity and transitivity. It is not assumed
 -- to be anti-symmetric.

src/Data/Trie.hs

@@ -1,11 +1,12 @@
-module Trie where
+module Data.Trie where
 
 import Data.Map.Lazy qualified as Map
 import Data.Map.Merge.Lazy qualified as Map
 
--- | Trie data structure to store a set of words of type i. Not necessarily
+-- | Trie data structure to store a set of words of type @i@. Not necessarily
 -- the most efficient implementation, but it's fine for our purposes. It can
--- be used to remove common prefixes from a set of words.
+-- be used to remove common prefixes from a list of words:
+-- @`toList` . `fromList` $ ls@.
 data Trie i
   = Leaf [i]
   | Node (Map.Map i (Trie i))
@@ -15,9 +16,11 @@ data Trie i
 empty :: Trie i
 empty = Leaf []
 
+-- | Set with a single word.
 singleton :: [i] -> Trie i
 singleton = Leaf
 
+-- | Insert a word into the trie.
 insert :: Ord i => [i] -> Trie i -> Trie i
 insert [] t = t
 insert w (Leaf []) = Leaf w
@@ -28,13 +31,18 @@ insert (a : w1) (Leaf (b : w2))
   | otherwise = Node (Map.fromList [(a, Leaf w1), (b, Leaf w2)])
 insert (a : w1) (Node m) = Node (Map.insertWith union a (Leaf w1) m)
 
+-- | Union of two tries.
 union :: Ord i => Trie i -> Trie i -> Trie i
 union (Leaf w) t = insert w t
 union t (Leaf w) = insert w t
 union (Node m1) (Node m2) =
   Node (Map.merge Map.preserveMissing Map.preserveMissing (Map.zipWithMatched (const union)) m1 m2)
 
--- Without common prefixes
+-- | Enumerates all words in the trie. Prefixes are not outputted.
 toList :: Trie i -> [[i]]
 toList (Leaf w) = [w]
 toList (Node m) = Map.foldMapWithKey (\a t -> fmap (a :) . toList $ t) m
+
+-- | Adds all words in the list to a trie.
+fromList :: Ord i => [[i]] -> Trie i
+fromList = foldr insert empty

src/Data/UnionFind.hs

@@ -0,0 +1,50 @@
+module Data.UnionFind where
+
+import Data.Map.Strict qualified as Map
+
+-- | A simple implementation of the Union-Find data structure. It does not have
+-- the optimal runtime bounds. Depending on the sequence of actions, the time
+-- might take O(n^2). Very simple and purely functional. My design goals:
+--
+-- * Pure interface, no state monad.
+-- * Generic element type, not restricted to `Int`.
+-- * No unnecessary optimisations.
+-- * O(1) initialisation, as not all elements are known in advance.
+newtype UnionFind x = MkUnionFind {unUnionFind :: Map.Map x x}
+
+-- The map data structure stores a 'parent' for each element. If an element
+-- has no parent, it is the root. If two elements have the same root, they are
+-- equivalent. The path-compression optimisation is used to make the tree
+-- flatter.
+
+-- | Initialises the union-find data structure, i.e., all elements disjoint.
+-- Runs in O(1).
+empty :: UnionFind x
+empty = MkUnionFind Map.empty
+
+-- | Checks whether two elements are equivalent. This functions does not use
+-- path-compression, as the interface is pure.
+equivalent :: Ord x => x -> x -> UnionFind x -> Bool
+equivalent x y (MkUnionFind m) = root x == root y
+ where
+  root z = maybe z root (Map.lookup z m)
+
+-- | Equates two elements, that is make two elements equivalent. This function
+-- does use path-compression, so that subsequent calls to `equivalent` are
+-- faster.
+equate :: Ord x => x -> x -> UnionFind x -> UnionFind x
+equate x y (MkUnionFind m1) =
+  let (rx, m2) = rootCP x m1 rx
+      (ry, m3) = rootCP y m2 ry
+   in if rx == ry
+        then MkUnionFind m3
+        else MkUnionFind (Map.insert rx ry m3)
+ where
+  rootCP z m r = case Map.lookup z m of
+    Nothing -> (z, m)
+    Just w -> Map.insert z r <$> rootCP w m r
+
+-- We zouden ook nog een rank optimalisatie kunnen (moeten?) doen. Maar dan
+-- moeten we meer onthouden. Verder zou ik een functie kunnen maken die
+-- een `equivalent` en `equate` combineert, dat kan namelijk wel met pad-
+-- compressie.

src/MealyRefine.hs

@@ -1,7 +1,7 @@
 module MealyRefine where
 
 import Mealy
-import Partition (Partition)
+import Data.Partition (Partition)
 
 import Control.Monad.ST (runST)
 import Copar.Algorithm (refine)

src/Merger.hs

@@ -1,6 +1,6 @@
 module Merger where
 
-import Partition
+import Data.Partition
 
 import Control.Monad (replicateM)
 import Control.Monad.IO.Class (liftIO)

src/Partition.hs

@@ -1,74 +0,0 @@
-module Partition (
-  module Partition,
-  module Data.Partition,
-) where
-
-import Preorder
-
-import Control.Monad.Trans.State.Strict (get, put, runState)
-import Data.Coerce (coerce)
-import Data.Map.Strict qualified as Map
-import Data.Partition (Partition (..), blockOfState, numStates, toBlocks)
-import Data.Partition.Common (Block (..))
-import Data.Vector qualified as V
-
--- | Returns the common refinement of two partitions. This is the coarsest
--- partition which is finer than either input, i.e., the greatest lower bound.
--- (If we put the finest partition on the top, and the coarsest on the bottom.)
-commonRefinement :: Partition -> Partition -> Partition
-commonRefinement p1 p2 =
-  let n = numStates p1
-      sa1 = (stateAssignment p1 V.!)
-      sa2 = (stateAssignment p2 V.!)
-      blockAtIdx i = do
-        (m, b) <- get
-        let key = (sa1 i, sa2 i)
-        case Map.lookup key m of
-          Just b0 -> return b0
-          Nothing -> do
-            put (Map.insert key b m, succ b)
-            return b
-      (vect, (_, nextBlock)) = runState (V.generateM n blockAtIdx) (Map.empty, 0)
-   in Partition{numBlocks = coerce nextBlock, stateAssignment = vect}
-
--- Could be made faster by doing what commonRefinement is doing but
--- stopping early. This is already much faster than what is in
--- the CoPaR library, so I won't bother.
-isRefinementOf2 :: Partition -> Partition -> Bool
-isRefinementOf2 refined original = comparePartitions refined original == Refinement
-
--- See comment at isRefinementOf2
-isEquivalent :: Partition -> Partition -> Bool
-isEquivalent p1 p2 = comparePartitions p1 p2 == Equivalent
-
--- Instead of checking whether one partition is a refinement of another AND
--- also checking vice versa. We can check the direction at once, computing the
--- common refinement only once. It saves some time.
-data Comparison
-  = Equivalent
-  | Refinement
-  | Coarsening
-  | Incomparable
-  deriving (Eq, Ord, Read, Show, Enum, Bounded)
-
--- We put the finer partitions above
-toPreorder :: Comparison -> PartialOrdering
-toPreorder Equivalent = EQ'
-toPreorder Refinement = GT'
-toPreorder Coarsening = LT'
-toPreorder Incomparable = IC'
-
--- See comment at isRefinementOf2
-comparePartitions :: Partition -> Partition -> Comparison
-comparePartitions p1 p2
-  | p1 == p2 = Equivalent
-  | otherwise =
-      let glb = commonRefinement p1 p2
-          n1 = numBlocks p1
-          n2 = numBlocks p2
-          n3 = numBlocks glb
-       in case (n1 == n3, n2 == n3) of
-            (True, True) -> Equivalent
-            (True, False) -> Refinement
-            (False, True) -> Coarsening
-            (False, False) -> Incomparable

src/StateIdentifiers.hs

@@ -1,7 +1,7 @@
 module StateIdentifiers where
 
 import SplittingTree
-import Trie qualified
+import Data.Trie qualified as Trie
 
 import Data.Map.Strict qualified as Map