{- |

Module : $Header$

Description : A abstract syntax for the TPTP-THF Syntax

Copyright : (c) A. Tsogias, DFKI Bremen 2011

License : GPLv2 or higher, see LICENSE.txt

Maintainer :

Stability :

Portability :

A Abstract Syntax for the TPTP-THF Input Syntax v5.1.0.2 taken from

<http://www.cs.miami.edu/~tptp/TPTP/SyntaxBNF.html>

-}

module THF.As where

-- A las Question: at the example of <source>: Sould <general_term> be also

-- tried when all ather cariations fail?

-- <TPTP_input> ::= <annotated_formula> | <include>

-- <thf_annotated> ::= thf(<name>,<formula_role>,<thf_formula><annotations>).

data TPTP_THF =

TPTP_THF_Annotated_Formula Name FormulaRole THFFormula Annotations

| TPTP_Include Include

| TPTP_Comment Comment

| TPTP_Defined_Comment DefinedComment

| TPTP_System_Comment SystemComment

-- | TPTP_Empty_Line

deriving (Show, Eq, Ord)

-- <comment> ::- <comment_line>|<comment_block>

-- <comment_line> ::- [%]<printable_char>*

-- <comment_block> ::: [/][*]<not_star_slash>[*][*]*[/]

-- <not_star_slash> ::: ([^*]*[*][*]*[^/*])*[^*]*

data Comment =

Comment_Line String

| Comment_Block [String]

deriving (Show, Eq, Ord)

-- <defined_comment> ::- <def_comment_line>|<def_comment_block>

-- <def_comment_line> ::: [%]<dollar><printable_char>*

-- <def_comment_block> ::: [/][*]<dollar><not_star_slash>[*][*]*[/]

data DefinedComment =

Defined_Comment_Line String

| Defined_Comment_Block [String]

deriving (Show, Eq, Ord)

-- <system_comment> ::- <sys_comment_line>|<sys_comment_block>

-- <sys_comment_line> ::: [%]<dollar><dollar><printable_char>*

-- <sys_comment_block> ::: [/][*]<dollar><dollar><not_star_slash>[*][*]*[/]

data SystemComment =

System_Comment_Line String

| System_Comment_Block [String]

deriving (Show, Eq, Ord)

-- <include> ::= include(<file_name><formula_selection>).

-- <formula_selection> ::= ,[<name_list>] | <null>

data Include =

I_Include FileName (Maybe NameList)

deriving (Show, Eq, Ord)

-- <annotations> ::= ,<source><optional_info> | <null>

data Annotations =

Annotations Source OptionalInfo

| Null

deriving (Show, Eq, Ord)

-- <formula_role> ::= <lower_word>

-- <formula_role> :== axiom | hypothesis | definition | assumption |

-- lemma | theorem | conjecture | negated_conjecture |

-- plain | fi_domain | fi_functors | fi_predicates |

-- type | unknown

data FormulaRole =

Axiom | Hypothesis | Definition | Assumption

| Lemma | Theorem | Conjecture | Negated_Conjecture

| Plain | Fi_Domain | Fi_Functors | Fi_Predicates

| Type | Unknown

deriving (Show, Eq, Ord)

-- <thf_formula> ::= <thf_logic_formula> | <thf_sequent>

data THFFormula =

TF_THF_Logic_Formula THFLogicFormula

| TF_THF_Sequent THFSequent

deriving (Show, Eq, Ord)

-- <thf_logic_formula> ::= <thf_binary_formula> | <thf_unitary_formula> |

-- <thf_type_formula> | <thf_subtype>

data THFLogicFormula =

TLF_THF_Binary_Formula THFBinaryFormula

| TLF_THF_Unitary_Formula THFUnitaryFormula

| TLF_THF_Type_Formula THFTypeFormula

| TLF_THF_Sub_Type THFSubType

deriving (Show, Eq, Ord)

-- <thf_binary_formula> ::= <thf_binary_pair> | <thf_binary_tuple> |

-- <thf_binary_type>

-- <thf_binary_pair> ::= <thf_unitary_formula> <thf_pair_connective>

-- <thf_unitary_formula>

data THFBinaryFormula =

TBF_THF_Binary_Pair THFUnitaryFormula THFPairConnective THFUnitaryFormula

| TBF_THF_Binary_Tuple THFBinaryTuple

| TBF_THF_Binary_Type THFBinaryType

deriving (Show, Eq, Ord)

-- <thf_binary_tuple> ::= <thf_or_formula> | <thf_and_formula> |

-- <thf_apply_formula>

-- <thf_or_formula> ::= <thf_unitary_formula> <vline> <thf_unitary_formula> |

-- <thf_or_formula> <vline> <thf_unitary_formula>

-- <thf_and_formula> ::= <thf_unitary_formula> & <thf_unitary_formula> |

-- thf_and_formula> & <thf_unitary_formula>

-- <thf_apply_formula> ::= <thf_unitary_formula> @ <thf_unitary_formula> |

-- <thf_apply_formula> @ <thf_unitary_formula>

data THFBinaryTuple =

TBT_THF_Or_Formula THFUnitaryFormula [THFUnitaryFormula]

| TBT_THF_And_Formula THFUnitaryFormula [THFUnitaryFormula]

| TBT_THF_Apply_Formula THFUnitaryFormula [THFUnitaryFormula]

deriving (Show, Eq, Ord)

-- <thf_unitary_formula> ::= <thf_quantified_formula> | <thf_unary_formula> |

-- <thf_atom> | <thf_tuple> | <thf_let> |

-- <thf_conditional> | (<thf_logic_formula>)

-- <thf_quantified_formula> ::= <thf_quantifier> [<thf_variable_list>] :

-- <thf_unitary_formula>

-- thf_unary_formula> ::= <thf_unary_connective> (<thf_logic_formula>)

-- <thf_let> ::= := [<thf_let_list>] : <thf_unitary_formula>

-- <thf_let_list> ::= <thf_defined_var> |

-- <thf_defined_var>,<thf_let_list>

-- <thf_conditional> ::= $itef(<thf_logic_formula>,<thf_logic_formula>,

-- <thf_logic_formula>)

-- <thf_variable_list> ::= <thf_variable> |

-- <thf_variable>,<thf_variable_list>

data THFUnitaryFormula =

TUF_THF_Quantified_Formula THFQuantifier [THFVariable] THFUnitaryFormula

| TUF_THF_Unary_Formula THFUnaryConnective THFLogicFormula

| TUF_THF_Atom THFAtom

| TUF_THF_Tuple THFTuple

| TUF_THF_Let [THFDefinedVar] THFUnitaryFormula

| TUF_THF_Conditional THFLogicFormula THFLogicFormula THFLogicFormula

| TUF_THF_Logic_Formula_Par THFLogicFormula

deriving (Show, Eq, Ord)

-- <thf_variable> ::= <thf_typed_variable> | <variable>

-- <thf_typed_variable> ::= <variable> : <thf_top_level_type>

data THFVariable =

TV_THF_Typed_Variable Variable THFTopLevelType

| TV_Variable Variable

deriving (Show, Eq, Ord)

-- <thf_type_formula> ::= <thf_typeable_formula> : <thf_top_level_type>

-- <thf_type_formula> :== <constant> : <thf_top_level_type>

data THFTypeFormula =

TTF_THF_Type_Formula THFTypeableFormula THFTopLevelType

| TTF_THF_Role_Type Constant THFTopLevelType

deriving (Show, Eq, Ord)

-- <thf_typeable_formula> ::= <thf_atom> | <thf_tuple> | (<thf_logic_formula>)

data THFTypeableFormula =

TTyF_THF_Atom THFAtom

| TTyF_THF_Tuple THFTuple

| TTyF_THF_Logic_Formula THFLogicFormula

deriving (Show, Eq, Ord)

-- <thf_subtype> ::= <constant> <subtype_sign> <constant>

-- <subtype_sign> == <<

data THFSubType =

TST_THF_Sub_Type Constant Constant

deriving (Show, Eq, Ord)

-- <thf_top_level_type> ::= <thf_logic_formula>

type THFTopLevelType = THFLogicFormula

-- <thf_unitary_type> ::= <thf_unitary_formula>

type THFUnitaryType = THFUnitaryFormula

-- <thf_binary_type> ::= <thf_mapping_type> | <thf_xprod_type> |

-- <thf_union_type>

-- <thf_mapping_type> ::= <thf_unitary_type> <arrow> <thf_unitary_type> |

-- <thf_unitary_type> <arrow> <thf_mapping_type>

-- <arrow> ::- >

-- <thf_xprod_type> ::= <thf_unitary_type> <star> <thf_unitary_type> |

-- <thf_xprod_type> <star> <thf_unitary_type>

-- <star> ::- *

-- <thf_union_type> ::= <thf_unitary_type> <plus> <thf_unitary_type> |

-- <thf_union_type> <plus> <thf_unitary_type>

-- <plus> ::- +

data THFBinaryType =

TBT_THF_Mapping_Type THFUnitaryType [THFUnitaryType]

| TBT_THF_Xprod_Type THFUnitaryType [THFUnitaryType]

| TBT_THF_Union_Type THFUnitaryType [THFUnitaryType]

deriving (Show, Eq, Ord)

-- <thf_atom> ::= <term> | <thf_conn_term>

-- %----<thf_atom> can also be <defined_type> | <defined_plain_formula> |

-- %----<system_type> | <system_atomic_formula>, but they are syntactically

-- %----captured by <term>.

-- <system_type> :== <atomic_system_word>

-- <system_atomic_formula> ::= <system_term>

data THFAtom =

TA_Term Term

| TA_THF_Conn_Term THFConnTerm

| TA_Defined_Type DefinedType

| TA_Defined_Plain_Formula DefinedPlainFormula

| TA_System_Type AtomicSystemWord

| TA_System_Atomic_Formula SystemTerm

deriving (Show, Eq, Ord)

-- <thf_tuple> ::= [] | [<thf_tuple_list>]

-- <thf_tuple_list> ::= <thf_unitary_formula> |

-- <thf_unitary_formula>,<thf_tuple_list>

-- THFTupleList must not be empty

type THFTuple = [THFUnitaryFormula]

-- <thf_defined_var> ::= <thf_variable> := <thf_logic_formula> |

-- (<thf_defined_var>)

data THFDefinedVar =

TDV_THF_Defined_Var THFVariable THFLogicFormula

| TDV_THF_Defined_Var_Par THFDefinedVar

deriving (Show, Eq, Ord)

-- <thf_sequent> ::= <thf_tuple> <gentzen_arrow> <thf_tuple> |

-- (<thf_sequent>)

-- <gentzen_arrow> ::= -->

data THFSequent =

TS_THF_Sequent THFTuple THFTuple

| TS_THF_Sequent_Par THFSequent

deriving (Show, Eq, Ord)

-- <thf_conn_term> ::= <thf_pair_connective> | <assoc_connective> |

-- <thf_unary_connective>

data THFConnTerm =

TCT_THF_Pair_Connective THFPairConnective

| TCT_Assoc_Connective AssocConnective

| TCT_THF_Unary_Connective THFUnaryConnective

deriving (Show, Eq, Ord)

-- <thf_quantifier> ::= <fol_quantifier> | ^ | !> | ?* | @+ | @-

-- <fol_quantifier> ::= ! | ?

data THFQuantifier =

ForAll -- !

| Exists -- ?

| Lambda_Binder -- ^

| Dependent_Product -- !>

| Dependent_Sum -- ?*

| Indefinite_Description -- @+

| Definite_Description -- @-

deriving (Show, Eq, Ord)

-- <thf_pair_connective> ::= <infix_equality> | <infix_inequality> |

-- <binary_connective>

-- <binary_connective> ::= <=> | => | <= | <~> | ~<vline> | ~&

-- <infix_equality> ::= =

-- <infix_inequality> ::= !=

data THFPairConnective =

Infix_Equality -- =

| Infix_Inequality -- !=

| Equivalent -- <=>

| Implication -- =>

| IF -- <=

| XOR -- <~>

| NOR -- ~|

| NAND -- ~&

deriving (Show, Eq, Ord)

-- <thf_unary_connective> ::= <unary_connective> | !! | ??

-- <unary_connective> ::= ~

data THFUnaryConnective =

Negation -- ~

| PiForAll -- !!

| SigmaExists -- ??

deriving (Show, Eq, Ord)

-- <assoc_connective> ::= <vline> | &

data AssocConnective =

OR -- |

| AND -- &

deriving (Show, Eq, Ord)

-- <defined_type> ::= <atomic_defined_word>

-- <defined_type> :== $oType | $o | $iType | $i | $tType |

-- $real | $rat | $int

data DefinedType =

DT_oType | DT_o | DT_iType | DT_i

| DT_tType | DT_real | DT_rat | DT_int

deriving (Show, Eq, Ord)

-- <defined_plain_formula> ::= <defined_plain_term>

-- <defined_plain_formula> :== <defined_prop> | <defined_pred>(<arguments>)

data DefinedPlainFormula =

DPF_Defined_Prop DefinedProp

| DPF_Defined_Formula DefinedPred Arguments

deriving (Show, Eq, Ord)

-- <defined_prop> :== <atomic_defined_word>

-- <defined_prop> :== $true | $false

data DefinedProp =

DP_True | DP_False

deriving (Show, Eq, Ord)

-- <defined_pred> :== <atomic_defined_word>

-- <defined_pred> :== $equal | $distinct | $itef | $less |

-- $lesseq | $greater | $greatereq | $evaleq |

-- $is_int | $is_rat

data DefinedPred =

Equal | Disrinct | Itef | Less

| Lesseq | Greater | Greatereq | Evaleq

| Is_int | Is_rat

deriving (Show, Eq, Ord)

-- <term> ::= <function_term> | <variable> | <conditional_term>

-- %----Conditional terms should not be used by THF.

-- Thus tey are not implemented.

data Term =

T_Function_Term FunctionTerm

| T_Variable Variable

deriving (Show, Eq, Ord)

-- <function_term> ::= <plain_term> | <defined_term> | <system_term>

data FunctionTerm =

FT_Plain_Term PlainTerm

| FT_Defined_Term DefinedTerm

| FT_System_Term SystemTerm

deriving (Show, Eq, Ord)

-- <plain_term> ::= <constant> | <functor>(<arguments>)

data PlainTerm =

PT_Plain_Term TPTPFunctor Arguments

| PT_Constant Constant

deriving (Show, Eq, Ord)

-- <constant> ::= <functor>

type Constant = TPTPFunctor

-- <functor> ::= <atomic_word>

type TPTPFunctor = AtomicWord

-- <defined_term> ::= <defined_atom> | <defined_atomic_term>

-- <defined_atomic_term> ::= <defined_plain_term>

data DefinedTerm =

DT_Defined_Atom DefinedAtom

| DT_Defined_Atomic_Term DefinedPlainTerm

deriving (Show, Eq, Ord)

-- <defined_atom> ::= <number> | <distinct_object>

data DefinedAtom =

DA_Number Number

| DA_Distinct_Object DistinctObject

deriving (Show, Eq, Ord)

-- <defined_plain_term> ::= <defined_constant> | <defined_functor>(<arguments>)

-- <defined_constant> ::= <defined_functor>

data DefinedPlainTerm =

DPT_Defined_Function DefinedFunctor Arguments

| DPT_Defined_Constant DefinedFunctor

deriving (Show, Eq, Ord)

-- <defined_functor> ::= <atomic_defined_word>

-- <defined_functor> :== $itett | $uminus | $sum | $difference |

-- $product | $to_int | $to_rat | $to_real

data DefinedFunctor =

Itett | Uminus | Sum | Difference

| Product | To_int | To_rat | To_real

deriving (Show, Eq, Ord)

-- <system_term> ::= <system_constant> | <system_functor>(<arguments>)

-- <system_constant> ::= <system_functor>

data SystemTerm =

ST_System_Term SystemFunctor Arguments

| ST_System_Constant SystemFunctor

deriving (Show, Eq, Ord)

-- <system_functor> ::= <atomic_system_word>

-- <upper_word> ::- <upper_alpha><alpha_numeric>*

type SystemFunctor = AtomicSystemWord

-- <variable> ::= <upper_word>

type Variable = String

-- <arguments> ::= <term> | <term>,<arguments>

-- at least one term is neaded

type Arguments = [Term]

-- <principal_symbol> :== <functor> | <variable>

data PrincipalSymbol =

PS_Functor TPTPFunctor

| PS_Variable Variable

deriving (Show, Eq, Ord)

-- <source> ::= <general_term>

-- <source> :== <dag_source> | <internal_source> | <external_source> |

-- unknown | [<sources>]

-- <internal_source> :== introduced(<intro_type><optional_info>)

-- <sources> :== <source> | <source>,<sources>

data Source =

S_Dag_Source DagSource

| S_Internal_Source IntroType OptionalInfo

| S_External_Source ExternalSource

| S_Sources [Source]

| S_Unknown

deriving (Show, Eq, Ord)

-- <dag_source> :== <name> | <inference_record>

-- <inference_record> :== inference(<inference_rule>,<useful_info>,

-- [<parent_list>])

-- <inference_rule> :== <atomic_word>

-- <parent_list> :== <parent_info> | <parent_info>,<parent_list>

data DagSource =

DS_Name Name

| DS_Inference_Record AtomicWord UsefulInfo [ParentInfo]

deriving (Show, Eq, Ord)

-- <parent_info> :== <source><parent_details>

-- <parent_details> :== :<general_list> | <null>

data ParentInfo =

PI_Parent_Info Source (Maybe GeneralList)

deriving (Show, Eq, Ord)

-- <intro_type> :== definition | axiom_of_choice | tautology | assumption

data IntroType =

IT_definition | IT_axiom_of_choice | IT_tautology | IT_assumption

deriving (Show, Eq, Ord)

-- <external_source> :== <file_source> | <theory> | <creator_source>

-- <theory> :== theory(<theory_name><optional_info>)

-- <creator_source> :== creator(<creator_name><optional_info>)

-- <creator_name> :== <atomic_word>

data ExternalSource =

ES_File_Source FileSource

| ES_Theory TheoryName OptionalInfo

| ES_Creator_Source AtomicWord OptionalInfo

deriving (Show, Eq, Ord)

-- <file_source> :== file(<file_name><file_info>)

-- <file_info> :== ,<name> | <null>

data FileSource =

FS_File FileName (Maybe Name)

deriving (Show, Eq, Ord)

-- <theory_name> :== equality | ac

data TheoryName =

Equality | Ac

deriving (Show, Eq, Ord)

-- <optional_info> ::= ,<useful_info> | <null>

type OptionalInfo = (Maybe UsefulInfo)

-- <useful_info> ::= <general_list>

-- <useful_info> :== [] | [<info_items>]

-- <info_items> :== <info_item> | <info_item>,<info_items>

type UsefulInfo = [InfoItem]

-- <info_item> :== <formula_item> | <inference_item> |

-- <general_function>

data InfoItem =

II_Formula_Item FormulaItem

| II_Inference_Item InferenceItem

| II_General_Function GeneralFunction

deriving (Show, Eq, Ord)

-- <formula_item> :== <description_item> | <iquote_item>

-- <description_item> :== description(<atomic_word>)

-- <iquote_item> :== iquote(<atomic_word>)

data FormulaItem =

FI_Description_Item AtomicWord

| FI_Iquote_Item AtomicWord

deriving (Show, Eq, Ord)

-- <inference_item> :== <inference_status> | <assumptions_record> |

-- <new_symbol_record> | <refutation>

-- <assumptions_record> :== assumptions([<name_list>])

-- <refutation> :== refutation(<file_source>)

-- <new_symbol_record> :== new_symbols(<atomic_word>,[<new_symbol_list>])

-- <new_symbol_list> :== <principal_symbol> |

-- <principal_symbol>,<new_symbol_list>

data InferenceItem =

II_Inference_Status InferenceStatus

| II_Assumptions_Record NameList

| II_New_Symbol_Record AtomicWord [PrincipalSymbol]

| II_Refutation FileSource

deriving (Show, Eq, Ord)

-- <inference_status> :== status(<status_value>) | <inference_info>

-- <inference_info> :== <inference_rule>(<atomic_word>,<general_list>)

-- <inference_rule> :== <atomic_word>

data InferenceStatus =

IS_Status StatusValue

| IS_Inference_Info AtomicWord AtomicWord GeneralList

deriving (Show, Eq, Ord)

-- <status_value> :== suc | unp | sap | esa | sat | fsa | thm | eqv | tac |

-- wec | eth | tau | wtc | wth | cax | sca | tca | wca |

-- cup | csp | ecs | csa | cth | ceq | unc | wcc | ect |

-- fun | uns | wuc | wct | scc | uca | noc

data StatusValue =

Suc | Unp | Sap | Esa | Sat | Fsa | Thm | Eqv | Tac

| Wec | Eth | Tau | Wtc | Wth | Cax | Sca | Tca | Wca

| Cup | Csp | Ecs | Csa | Cth | Ceq | Unc | Wcc | Ect

| Fun | Uns | Wuc | Wct | Scc | Uca | Noc

deriving (Show, Eq, Ord)

-- <name_list> ::= <name> | <name>,<name_list>

-- the list must mot be empty

type NameList = [Name]

-- <general_term> ::= <general_data> | <general_data>:<general_term> |

-- <general_list>

data GeneralTerm =

GT_General_Data GeneralData

| GT_General_Data_Term GeneralData GeneralTerm

| GT_General_List GeneralList

deriving (Show, Eq, Ord)

-- <general_data> ::= <atomic_word> | <general_function> |

-- <variable> | <number> | <distinct_object> |

-- <formula_data>

-- <general_data> :== bind(<variable>,<formula_data>)

data GeneralData =

GD_Atomic_Word AtomicWord

| GD_Variable Variable

| GD_Number Number

| GD_Distinct_Object DistinctObject

| GD_Formula_Data FormulaData

| GD_Bind Variable FormulaData

| GD_General_Function GeneralFunction

deriving (Show, Eq, Ord)

-- <general_function> ::= <atomic_word>(<general_terms>)

-- general_terms must not be empty

data GeneralFunction =

GF_General_Function AtomicWord GeneralTerms

deriving (Show, Eq, Ord)

-- <formula_data> ::= $thf(<thf_formula>) | $tff(<tff_formula>) |

-- $fof(<fof_formula>) | $cnf(<cnf_formula>) |

-- $fot(<term>)

-- only thf is used here

data FormulaData =

THF_Formula THFFormula

deriving (Show, Eq, Ord)

-- <general_list> ::= [] | [<general_terms>]

type GeneralList = GeneralTerms

-- <general_terms> ::= <general_term> | <general_term>,<general_terms>

type GeneralTerms = [GeneralTerm]

-- <name> ::= <atomic_word> | <integer>

data Name =

N_Atomic_Word AtomicWord

| N_Integer String

deriving (Show, Eq, Ord)

-- <atomic_word> ::= <lower_word> | <single_quoted>

data AtomicWord =

A_Lower_Word LowerWord

| A_Single_Quoted SingleQuoted

deriving (Show, Eq, Ord)

-- <atomic_system_word> ::= <dollar_dollar_word>

-- <dollar_dollar_word> ::- <dollar><dollar><lower_word>

-- <dollar> ::: [$]

type AtomicSystemWord = LowerWord

-- <number> ::= <integer> | <rational> | <real>

-- <real> ::- (<signed_real>|<unsigned_real>)

-- <signed_real> ::- <sign><unsigned_real>

-- <unsigned_real> ::- (<decimal_fraction>|<decimal_exponent>)

-- <rational> ::- (<signed_rational>|<unsigned_rational>)

-- <signed_rational> ::- <sign><unsigned_rational>

-- <unsigned_rational> ::- <decimal><slash><positive_decimal>

-- <integer> ::- (<signed_integer>|<unsigned_integer>)

-- <signed_integer> ::- <sign><unsigned_integer>

-- <unsigned_integer> ::- <decimal>

-- <decimal> ::- (<zero_numeric>|<positive_decimal>)

-- <positive_decimal> ::- <non_zero_numeric><numeric>*

-- <decimal_exponent> ::- (<decimal>|<decimal_fraction>)<exponent><decimal>

-- <decimal_fraction> ::- <decimal><dot_decimal>

-- <dot_decimal> ::- <dot><numeric><numeric>*

-- <sign> ::: [+-]

-- <dot> ::: [.]

-- <exponent> ::: [Ee]

-- <slash> ::: [/]

-- <zero_numeric> ::: [0]

-- <non_zero_numeric> ::: [1-9]

-- <numeric> ::: [0-9]

data Number =

Num_Integer String

| Num_Rational String

| Num_Real String

deriving (Show, Eq, Ord)

-- <file_name> ::= <single_quoted>

type FileName = SingleQuoted

-- <single_quoted> ::- <single_quote><sq_char><sq_char>*<single_quote>

-- <single_quote> ::: [']

-- <sq_char> ::: ([\40-\46\50-\133\135-\176]|[\\]['\\])

type SingleQuoted = String

-- <distinct_object> ::- <double_quote><do_char>*<double_quote>

-- <do_char> ::: ([\40-\41\43-\133\135-\176]|[\\]["\\])

-- <double_quote> ::: ["]

type DistinctObject = String

-- <lower_word> ::- <lower_alpha><alpha_numeric>*

-- <alpha_numeric> ::: (<lower_alpha>|<upper_alpha>|<numeric>|[_])

-- <lower_alpha> ::: [a-z]

-- <upper_alpha> ::: [A-Z]

-- <numeric> ::: [0-9]

type LowerWord = String

--------------------------------------------------------------------------------

-- Data structures used in Logic_THF

data SignTHF = UNDEFINEDSIGN deriving (Eq, Ord, Show)

--

data SymbolTHF = UNDEFINEDSYMOL deriving (Show, Eq, Ord)