{- | Module : $Header$

- Description : Abstract syntax for the Generic Modal Prover

- Copyright : (c) Georgel Calin & Lutz Schroeder, DFKI Lab Bremen

- License : Similar to LGPL, see HetCATS/LICENSE.txt or LIZENZ.txt

- Maintainer : g.calin@jacobs-university.de

- Stability : provisional

- Portability : non-portable (various -fglasgow-exts extensions)

-

- Provides data structures and show instances for the more general data types

- used in the implementation of the Generic Modal Prover -}

module GMP.GMPAS where

import qualified Data.Set as Set

{- | Datatype with which formulas are handled in the implementation

- A formula will recurse in a tree-like manner via negation, junction or modal

- application until one of "true", "false" or "variable" -}

data Formula a = F

| T

| Neg (Formula a)

| Junctor (Formula a) Junctor (Formula a)

| Mapp (Mop a) (Formula a)

| Var Char (Maybe Integer)

deriving (Eq, Ord)

instance Show a => Show (Formula a) where

show f = case f of

F -> "F"

T -> "T"

Neg x -> "~" ++ show x

Junctor x j y -> "(" ++ show x ++ " " ++ show j ++ " " ++ show y ++ ")"

Mapp m x -> show m ++ show x

Var c i -> case i of

Nothing -> [c]

Just ii -> [c] ++ show ii

-- | Junctors for "and", "or", "implies", "is implied" and "if and only if"

data Junctor = And | Or | If | Fi | Iff

deriving (Eq, Ord)

instance Show Junctor where

show j = case j of

And -> "/\\"

Or -> "\\/"

If -> "->"

Fi -> "<-"

Iff -> "<->"

-- | Datatype for the modal operator

data Mop a = Mop a Otype

deriving (Eq, Ord)

instance Show a => Show (Mop a) where

show m = case m of

Mop x Square -> "[" ++ show x ++ "]"

Mop x Angle -> "<" ++ show x ++ ">"

-- | Type of the modal operator used in the modal aplication

data Otype = Square | Angle

deriving (Eq, Ord)

-- | Datatype of the modal index of K modal logic

data ModalK = ModalK ()

deriving (Eq, Ord)

instance Show ModalK where

show (ModalK ()) = ""

-- | Datatype of the modal index of KD modal logic

data ModalKD = ModalKD ()

deriving (Eq, Ord)

instance Show ModalKD where

show (ModalKD ()) = ""

-- | Datatype of the modal index of Graded modal logic

data GML = GML Int

deriving (Eq, Ord)

instance Show GML where

show (GML n) = show n

-- | Datatype of the modal index of Coalition logic

data CL = CL (Set.Set Int) Int

deriving (Eq, Ord)

instance Show CL where

show (CL i m) = let showSet s =

case (Set.size s) of

0 -> ""

1 -> let (aux, next) = Set.deleteFindMin s

in show aux ++ showSet next

_ -> let (aux, next) = Set.deleteFindMin s

in show aux ++ "," ++ showSet next

in "{" ++ showSet i ++ "}" ++ ":" ++ show m

-- | Datatype of the modal index of Majority logic

data ML = ML Int | W

deriving (Eq, Ord)

instance Show ML where

show x = case x of

ML n -> show n

W -> "W"

-- | Datatype of the generic (string) modal index

data Kars = Kars [Char]

deriving (Eq, Ord)

instance Show Kars where

show (Kars l) = show l

-- | Datatype for the propositional clauses

data PropClause = Pimplies [Int] [Int]

deriving Show

-- | Datatype for the modal clauses

data ModClause a = Mimplies [Formula a] [Formula a]

deriving (Show, Eq, Ord)

-- | For Debugging set it to True

debug :: Bool

debug = False --True