48c48,49
< This TR is an extension to the ISO/IEC 13211--1 Prolog standard, adopting a similar structure. In particular, this TR adds new subclauses to, or modifies existing subclauses of ISO/IEC 13211--1.
---
> This TR is an extension to the ISO/IEC 13211--1 Prolog standard, adopting a similar structure. In particular, this TR adds new sections and subsections to, or modifies existing sections of ISO/IEC 13211--1.
> 
107d107
< 	\item  A Reference implementation.
115c115
< NOTE --- The limitations, expressed in clause 1, Scope, of ISO/IEC 13211--1:1995 apply to this TR.
---
> NOTE --- The limitations, expressed in section 1, Scope, of ISO/IEC 13211--1:1995 apply to this TR.
134c134
< \textsl{For the purposes of this TR, the following Definitions are added to the ones specified in ISO/IEC 13211--1:}
---
> \textsl{For the purposes of this TR, the following definitions are added to the ones specified in ISO/IEC 13211--1:}
138,139d137
< \paragraph{alternative:} A compound term with principal functor \code{(;)/2} or with principal functor \code{('|')} with each argument being a body (of a grammar-rule). 
< 
142c140
< \paragraph{clause-term:} A read-term \code{T.} in Prolog text where \code{T} does not have principal functor \code{(:-)/1} nor principal functor \code{(-->)/2.} (This definition replaces subclause 3.33 of ISO/IEC 13211--1).
---
> \paragraph{clause-term:} A read-term \code{T.} in Prolog text where \code{T} does not have principal functor \code{(:-)/1} nor principal functor \code{(-->)/2.} (This definition replaces section 3.33 of ISO/IEC 13211--1).
146,149c144,145
< \paragraph{cover,a terminal-sequence by a non-terminal (resp. a body) :}  A
< terminal sequence is covered by a non-terminal (resp. a body)  if the non-terminal
< (resp. the body) generates the terminal sequence. Alternatively if the non-terminal (resp. body)
< parses the terminal sequence.
---
> \paragraph{cover, a terminal-sequence by a non-terminal resp. a body:}  A terminal sequence is covered by a non-terminal resp. a body if the non-terminal resp. the body generates the terminal sequence,
> respectively parses the terminal sequence.
153c149
< \paragraph{expansion (of a grammar-rule):} The preparation for execution (cf. ISO/IEC 13211--1, subclause 7.5.1) of a grammar rule.
---
> \paragraph{expansion (of a grammar-rule):} The preparation for execution (cf. ISO/IEC 13211--1, section 7.5.1) of a grammar rule.
157c153,155
< \paragraph{generating (wrt. a definite clause grammar):} Producing terminal-sequences of that definite clause grammar, obeying semicontexts, if any.
---
> \paragraph{generating (wrt. a definite clause grammar):} Producing terminal-sequences of that definite clause grammar, obeying right-hand-contexts, if any.
> 
> \paragraph{grammar-body-alternative:} A compound term with principal functor \code{(;)/2} or with principal functor \code{('|')} with each argument being a body (of a grammar-rule). 
161c159,161
< \paragraph{grammar-body-element:} A grammar-body-cut (the atom \code{!}), or a grammar-goal, or a non-terminal, or a terminal-sequence.
---
> \paragraph{grammar-body-element:} A grammar-body-cut (the atom \code{!}), or a grammar-body-goal, or a non-terminal, or a terminal-sequence.
> 
> \paragraph{grammar-body-goal:} A compound term with principal functor \code{\{\}/1} whose argument is a goal. 
167c167
< \paragraph{grammar-goal:} A compound term with principal functor \code{\{\}/1} whose argument is a goal. 
---
> \paragraph{grammar-body-terminals:} A terminal-sequence. 
171c171
< \paragraph{grammar-rule-body:} The second argument of a grammar-rule. A grammar-body-sequence, or an alternative, or a grammar-body-not,  or a grammar-body-element. 
---
> \paragraph{grammar-rule-body:} The second argument of a grammar-rule. A grammar-body-sequence, or a grammar-body-alternative, or a grammar-body-not,  or a grammar-body-element. 
173,174c173,175
< % the next definition is changed JPEH. 
< \paragraph{grammar-rule-head:}\label{defGrammarRuleHead} The first argument of a grammar-rule. 
---
> \paragraph{grammar-rule-term:} A read-term \code{T.} where \code{T} is a grammar-rule. 
> 
> \paragraph{head (of a grammar-rule):}\label{defGrammarRuleHead} The first argument of a grammar-rule. 
177c178
< second argument is a semicontext (cf Definition \ref{defSemiContext}). 
---
> second argument is a right hand context (cf definition \ref{defRightHandContext}). 
183c184
< \paragraph{non-terminal indicator:}\label{defNonTerminalInd} A compound term \code{A//N} where \code{A} is an atom and \code{N} is a non-negative integer, denoting one particular non-terminal (cf \ref{ssection:nonterminalIndicator}). 
---
> \paragraph{non-terminal indicator:} A compound term \code{A//N} where \code{A} is an atom and \code{N} is a non-negative integer, denoting one particular non-terminal (cf \ref{ssection:nonterminalIndicator}). 
185c186
< \paragraph{parsing (wrt. a definite clause grammar):} Successively accepting or consuming terminal-sequences, assigning them to corresponding non-terminals and obeying  semicontexts, if any.
---
> \paragraph{parsing (wrt. a definite clause grammar):} Successively accepting or consuming terminal-sequences, assigning them to corresponding non-terminals and obeying  right-hand-contexts, if any.
189c190
< \paragraph{semicontext:}\label{defSemiContext} A terminal-sequence occurring as optional second argument of a grammar-rule-head, constraining parsing (respectively generation) by this grammar rule. 
---
> \paragraph{right-hand-context:}\label{defRightHandContext} A terminal-sequence occurring as optional second argument of a grammar-rule-head, constraining parsing, respectively generation, by this grammar rule. 
196c197,199
< \paragraph{terminal-sequence:}\label{defTerminalSequence} A list (cf. ISO/IEC 13211--1, subclauses 3.99, 6.3.5 and 6.3.1.3) whose first argument, if any, is a terminal (of a grammar), and the second argument, if any, is a terminal-sequence.
---
> \paragraph{terminal-sequence:}\label{defTerminalSequence} A list (cf. ISO/IEC 13211--1, sections 3.99, 6.3.5 and 6.3.1.3) whose first argument, if any, is a terminal (of a grammar), and the second argument, if any, is a terminal-sequence.
> 
> \paragraph{terminal-sequence, comprehensive:} Terminal sequence containing a (possibly empty) prefix covered (cf. Definition 3.4) by a grammar-rule-body, i.e. accepted resp. generated by \code{phrase/3} (cf \ref{sssection:phraseSpecification}) .
198c201
< \paragraph{terminal-sequence, comprehensive:} Terminal sequence containing a (possibly empty) prefix covered (cf. Definition 3.5) by a grammar-rule-body, i.e. accepted resp. generated by \code{phrase/3} (cf \ref{sssection:phraseSpecification}) .
---
> % Klaus: I think it's better to mention phrase/3, because the definition was un-understandable else. Removed the i.e. clause in the next defi.
200c203
< \paragraph{terminal-sequence, remaining:} Rest of comprehensive terminal-sequence without the leading terminal-sequence covered (cf. Definition 3.5) by a grammar-rule-body.
---
> \paragraph{terminal-sequence, remaining:} Rest of comprehensive terminal-sequence without the leading terminal-sequence covered (cf. Definition 3.4) by a grammar-rule-body.
204d206
< \newpage
244c246
< NOTE --- This extends the corresponding subclause of ISO/IEC 13211--1.
---
> NOTE --- This extends corresponding section of ISO/IEC 13211--1.
260c262
< \textsl{The corresponding subclause in the ISO/IEC 13211--1 Prolog standard is modified as follows:}\\
---
> \textsl{The corresponding section in the ISO/IEC 13211--1 Prolog standard is modified as follows:}\\
268c270
< \textsl{The corresponding subclause in the ISO/IEC 13211--1 Prolog standard is modified as follows:}\\
---
> \textsl{The corresponding section in the ISO/IEC 13211--1 Prolog standard is modified as follows:}\\
284c286
< \textsl{Please see subclause \ref{ssection:grammarRuleOperator} for the new predefined operators that this TR adds to the ISO/IEC 13211--1 Prolog standard.}
---
> \textsl{Please see subsection \ref{ssection:grammarRuleOperator} for the new predefined operators that this TR adds to the ISO/IEC 13211--1 Prolog standard.}
301c303
< \textsl{The text near the end of this subclause in the ISO/IEC 13211--1 Prolog standard is modified as follows:}\\
---
> \textsl{The text near the end of this section in the ISO/IEC 13211--1 Prolog standard is modified as follows:}\\
317c319
< \textsl{The following subclause extends, with the specified number, the corresponding ISO/IEC 13211--1 subclause.}
---
> \textsl{The following subsection extends, with the specified number, the corresponding ISO/IEC 13211--1 section.}
329c331
< \textsl{The first paragraph of this subclause on ISO/IEC 13211--1 is modified as follows:}\\
---
> \textsl{The first paragraph of this section on ISO/IEC 13211--1 is modified as follows:}\\
337c339
< \textsl{The corresponding subclause in the ISO/IEC 13211--1 is modified as follows:}\\
---
> \textsl{The corresponding section in the ISO/IEC 13211--1 is modified as follows:}\\
376c378
< \textsl{The corresponding subclause in the ISO/IEC 13211--1 is modified as follows:}\\
---
> \textsl{The corresponding section in the ISO/IEC 13211--1 is modified as follows:}\\
388c390
< NOTE --- Subclauses 7.5 and 7.6 define how clauses become part of the database.\\
---
> NOTE --- Subsections 7.5 and 7.6 define how clauses become part of the database.\\
391c393
< \textsl{The following subclause modifies, with the specified number, the corresponding ISO/IEC 13211--1 subclause:}
---
> \textsl{The following subsection modifies, with the specified number, the corresponding ISO/IEC 13211--1 section:}
409c411
< NOTE --- Subclause \ref{section:logicalExpansion} of this TR defines how a grammar rule in Prolog text is expanded into an equivalent clause when Prolog text is prepared for execution.
---
> NOTE --- Section \ref{section:logicalExpansion} of this TR defines how a grammar rule in Prolog text is expanded into an equivalent clause when Prolog text is prepared for execution.
412c414
< \paragraph{Semicontexts} ~\\
---
> \paragraph{Right-hand contexts} ~\\
415c417
< ~ & \code{semicontext term =} & \code{term}\\
---
> ~ & \code{right hand context term =} & \code{term}\\
418c420
< Condition: & semicontext term is a list\\
---
> Condition: & Rright hand context term is a list\\
420c422
< ~ & \code{semicontext =} & \code{semicontext term}\\
---
> ~ & \code{right hand context =} & \code{right hand context term}\\
426,428c428,430
< NOTE --- Subclause \ref{section:logicalExpansion} of this TR, \code{dcg\_rule/4}, first clause, defines how a semicontext in a grammar rule is expanded when Prolog text is prepared for execution.
< % Modified JPEH.
< % Accepted and corrected KD
---
> NOTE --- Section \ref{section:logicalExpansion} of this TR, rule \%02\% and rule \%04\%, defines how a right hand context in a grammar rule is expanded when Prolog text is prepared for execution.
> 
> 
434c436
< Extend the operator table of subclause 6.3.4.4 of ISO/IEC 13211--1 as follows: \\
---
> Extend the operator table of section 6.3.4.4 of ISO/IEC 13211--1 as follows: \\
447c449
< NOTE --- The operator \code{(-->)/2}, specified in subclause 6.3.4.4 of the ISO/IEC 13211--1 Prolog standard, is used as the principal functor of grammar rules.
---
> NOTE --- The operator \code{(-->)/2}, specified in section 6.3.4.4 of the ISO/IEC 13211--1 Prolog standard, is used as the principal functor of grammar rules.
454c456
< \textsl{The following subclause extends, with the specified number, the corresponding ISO/IEC 13211--1 subclause:}
---
> \textsl{The following subsection extends, with the specified number, the corresponding ISO/IEC 13211--1 section:}
467c469
<  subclause 7.4.2 of the ISO/IEC 13211--1 Prolog standard.
---
>  section 7.4.2 of the ISO/IEC 13211--1 Prolog standard.
473c475
< of subclause 6.24 of ISO/IEC 13211-2:2000.
---
> of section 6.24 of ISO/IEC 13211-2:2000.
481c483
< \textsl{The following subclause extends subclauses 6.8 and 7.2.2 of ISO/IEC 13211--2 Prolog Modules:}
---
> \textsl{The following subsection extends sections 6.8 and 7.2.2 of ISO/IEC 13211--2 Prolog Modules:}
485c487
< The following property is added to the list of predicate properties of subclause 6.8
---
> The following property is added to the list of predicate properties of section 6.8
489c491
< 	\item \code{expanded\_from(A//N)} --- The predicate resp. callable with predicate indicator \code{A/(N+2)} results from the expansion of a grammar rule with non-terminal indicator \code{A//N}, (cf. Definition 3.18 and subclause \ref{ssection:nonterminalIndicator}). 
---
> 	\item \code{expanded\_from(A//N)} --- The predicate resp. callable with predicate indicator \code{A/(N+2)} results from the expansion of a grammar rule with non-terminal indicator \code{A//N}
492,493d493
< \medskip
< 
495c495
< NOTE  --- a predicate property is the second argument of the built-in predicate \code{predicate\_property(Callable, Property)}, cf. subclause 6.8 of ISO/IEC 13211--2.\\
---
> NOTE  --- a predicate property is the second argument of the built-in predicate \code{predicate\_property(Callable, Property)}, cf. section 6.8 of ISO/IEC 13211--2.\\
503a504
> 
514c515
< NOTE --- In the context of a grammar rule, \textsl{terminals} represent tokens of some language, and \textsl{non-terminals} represent sequences of tokens (see, respectively, Definitions 3.23 and 3.17).
---
> NOTE --- In the context of a grammar rule, \textsl{terminals} represent tokens of some language, and \textsl{non-terminals} represent sequences of tokens (see, respectively, definitions 3.19 and 3.25).
518c519
< flag "double\_quotes" has value "chars"; see subclauses 6.3.7 and 6.4.6 of ISO/IEC 13211--1. 
---
> flag "double\_quotes" has value "chars"; see sections 6.3.7 and 6.4.6 of ISO/IEC 13211--1. 
576c577
< where \code{GRHead}, the head(of a grammar rule) (cf. Definition 3.15), can be rewritten by \code{GRBody}, its body(of a grammar rule) (cf. Definition 3.14). The head and the body of grammar rules are constructed from \textsl{non-terminals}, \textsl{terminals} and \textsl{control constructs}. The head(of a grammar rule) is a non-terminal or the conjunction of a non-terminal and, following, a terminal-sequence (a \textsl{semicontext}, see \ref{sssection:rightHandcontext}):
---
> where \code{GRHead}, the head(of a grammar rule) (cf. Definition 3.16), can be rewritten by \code{GRBody}, its body(of a grammar rule) (cf. Definition 3.1). The head and the body of grammar rules are constructed from \textsl{non-terminals}, \textsl{terminals} and \textsl{control constructs}. The head(of a grammar rule) is a non-terminal or the conjunction of a non-terminal and, following, a terminal-sequence (a \textsl{right-hand-context}, see \ref{sssection:rightHandcontext}):
581c582
< NonTerminal, SemiContext --> GRBody. \end{verbatim}
---
> NonTerminal, RightHandContext --> GRBody. \end{verbatim}
586c587
< The control constructs that may be used in a body are described in subclause \ref{ssection:controlConstructs}. An empty body is represented by an empty terminal sequence:
---
> The control constructs that may be used in a body are described in subsection \ref{ssection:controlConstructs}. An empty body is represented by an empty terminal sequence:
595c596
< \subsubsection{Semicontexts}
---
> \subsubsection{Right-hand-contexts}
605c606
< A \textsl{semicontext} is a terminal-sequence (see \ref{defTerminalSequence}), as an optional second argument of the head of a grammar rule (see \ref{defGrammarRuleHead}). A semicontext contains terminals that are prefixed to the remaining terminal-sequence after successful application of the grammar rule.
---
> A \textsl{right-hand-context} is a terminal-sequence (see \ref{defTerminalSequence}), as an optional second argument of the head of a grammar rule (see \ref{defGrammarRuleHead}). A right-hand-context contains terminals that are prefixed to the remaining terminal-sequence after successful application of the grammar rule.
633c634
< Another example may be a small grammar rule with semicontext:
---
> Another example may be a small grammar rule with right-hand-context:
665,666c666,667
< 1\hspace{1.5em} In case of parsing, as soon as \code{phrase2} and \code{phrase3} have successfully parsed the comprehensive terminal-sequence (input list), the terminal \code{word} is prefixed to the remaining terminal-sequence. \code{word} is then the first terminal to be consumed in further parsing after \code{phrase1}. Thus further parsing is constrained by the semicontext.\\  
< % process from path JPEH  March 28th Simplified second sentence. JPEH
---
> 1\hspace{1.5em} In case of parsing, as soon as \code{phrase2} and \code{phrase3} have successfully parsed the comprehensive terminal-sequence (input list), the terminal \code{word} is prefixed to the remaining terminal-sequence. \code{word} is then the first terminal to be consumed in further parsing after \code{phrase1}. Thus the path of further parsing is constrained by the right-hand-context.\\  
> % process from path JPEH
670,676c671,673
< 2\hspace{1.5em} The concepts \textsl{comprehensive terminal-sequence} resp. \textsl{remaining terminal-sequence} are often called \textsl{input list} resp. \textsl{output list}. This is misleading, because it only considers  the case of parsing using  a grammar. There a terminal list shall be parsed wrt. non-terminals, and there will be a  remainder after the parsing step. The inverse case, generating sentences by expanding grammars, where the comprehensive terminal-sequence is the real output list, is ignored by such wording.\\
< % Above par modified JPEH  also March 2014 
< % KD In former versions of the Draft (by Paulo) only the concepts of input list and output list were used.
< % The meaning was that during parsing a nonterminal consumes some terminals from the (larger) input list,
< % and there remains a (smaller) output list, subject to following parsing. But for generating it is the opposite,
< % there the output is larger (i.e. contains more terminals) than the input list. The wording input list and
< % output list is very colloquial, therefore shall be a clarification here.
---
> 2\hspace{1.5em} The concepts \textsl{comprehensive terminal-sequence} resp. \textsl{remaining terminal-sequence} are often named \textsl{input list} resp. \textsl{output list}. This is misleading, because it only considers  the case of parsing using  a grammar. There a terminal list shall be parsed wrt. non-terminals, and there will be a  remainder after the parsing step. The inverse case, generating sentences by expanding grammars, where the comprehensive terminal-sequence is the real output list, is ignored by such wording.\\
> % Above par modified JPEH
> % KD OK
712c709
< 4\hspace{1.5em} It should be noted that \code{phrase/2} (cf \ref{sssection:bootstrappedPredicates}) cannot succeed when applied to a grammar rule, whose head contains a non empty semicontext, as in the case above.\\
---
> 4\hspace{1.5em} It should be noted that \code{phrase/2} (cf \ref{sssection:bootstrappedPredicates}) cannot succeed when applied to a grammar rule, whose head contains a non empty right-hand context, as in the case above.\\
717c714
< 5 \hspace{1.5em} Some processors allow a cut in the semicontext; e.g.\\ 
---
> 5 \hspace{1.5em} Some processors allow a cut in the right-hand context; e.g.\\ 
722c719
< Thus this TR does not permit a cut in the semicontext.
---
> Thus this TR does not permit a cut in the right hand context.
744c741
< 2\hspace{1.5em}The concept of non-terminal indicator is similar to the concept of \textsl{predicate indicator} defined in subclauses 3.131 and 7.1.6.6 of the ISO/IEC 13211--1 Prolog. Non-terminal indicators may be used in exception terms thrown when processing or using grammar rules. In addition, non-terminal indicators may appear at some places, where a predicate indicator as defined in ISO/IEC 13211--1 can appear. See \ref{sssection:prologDirectives}.  Furthermore non-terminal indicators may be used in a predicate property (cf. subsection \ref{ssection:predicateProperties}). In particular, using non-terminal indicators in predicate directives allows the details of the expansion of grammar rules into Prolog clauses to be abstracted.
---
> 2\hspace{1.5em}The concept of non-terminal indicator is similar to the concept of \textsl{predicate indicator} defined in sections 3.131 and 7.1.6.6 of the ISO/IEC 13211--1 Prolog. Non-terminal indicators may be used in exception terms thrown when processing or using grammar rules. In addition, non-terminal indicators may appear at some places, where a predicate indicator as defined in ISO/IEC 13211--1 can appear. See \ref{sssection:prologDirectives}.  Furthermore non-terminal indicators may be used in a predicate property (cf. subsection \ref{ssection:predicateProperties}). In particular, using non-terminal indicators in predicate directives allows the details of the expansion of grammar rules into Prolog clauses to be abstracted.
778,779d774
< \begin{comment}
< % was decided on Istanbul conference. Contents should occur in 7.15.7
793,794c788,789
< \code{\{\}/1} is a functor of a \code{grammar-goal}  \{prolog\_goal\} (cf. Definition 3.12). After expansion 
< \code{prolog\_goal} is unchanged and is handled as a ordinary prolog goal according to subclause 7.7 of ISO/IEC 13211-1 Prolog.\\
---
> \code{\{\}/1} is a functor of a \code{grammar-body-goal}  \{prolog\_goal\} (cf. Definition 3.10). After expansion 
> \code{prolog\_goal} is unchanged and is handled as a ordinary prolog goal according to section 7.7 of ISO/IEC 13211-1 Prolog.\\
798c793
< NOTE --- The ISO/IEC 13211--1 Prolog standard defines, in subclause 6.3.6, a \textsl{curly bracketed term} as a compound term with principal functor \code{'\{\}'/1}, whose argument may also be expressed by enclosing its argument in curly brackets.
---
> NOTE --- The ISO/IEC 13211--1 Prolog standard defines, in section 6.3.6, a \textsl{curly bracketed term} as a compound term with principal functor \code{'\{\}'/1}, whose argument may also be expressed by enclosing its argument in curly brackets.
817d811
< \end{comment}
824,825d817
< 
< 
827c819
< This subclause describes the meaning of special non-terminals which are part of grammar rules: \\
---
> This subsection describes the meaning of special non-terminals which are part of grammar rules: \\
829,830c821
< 
< \medskip\noindent
---
> \noindent
836d826
< \code{\{\}//1}\\ 
838c828
< \code{phrase//1} \\
---
> \code{\{\}//1}\\ 
840,841c830,832
< \code{!//0}, and\\
< \code{(->)//2} in an \code{if-then-else}.\\ 
---
> \code{!//0}\\
> \code{(->)//2} in an \code{if-then-else}, and\\ 
> \code{phrase//1}. \\
843,844c834,835
< % moved to here. JPEH 
< % agreed. KD
---
> \medskip
> \medskip
846,849c837,838
< Expansion of grammar control constructs is not simply a replacement by Prolog control constructs. 
< For every grammar control construct there is a formal definition in the formal definition of \code{phrase/3} in subclause \ref{section:logicalExpansion}.
< The correspondence between the following subclauses and the corresponding formal definitions is given by the 
< principal functor of the first argument of the clauses of predicate \code{dcg\_cbody/4} in subclause \ref{section:logicalExpansion}.\\
---
> After preparation for execution of Grammar Rules, named ``Grammar Rule expansion'' or ``expansion'' for short, these non-terminals, with exception of phrase//1, result in control constructs, respectively built-in predicates of ISO/IEC 13211-1 Prolog. \\
> Expansion of grammar control constructs is not simply a replacement by Prolog control constructs. \\
853,855c842,843
< After preparation for execution of Grammar Rules, named ``Grammar Rule expansion'' or ``expansion'' for short, these non-terminals, with exception of phrase//1, result in control constructs, respectively built-in predicates of ISO/IEC 13211-1 Prolog. \\
< Grammar Rule expansion is defined by describing it wrt. the built-in predicate \code{phrase/3}  
< (see subclauses \ref{sssection:phraseSpecification} and \ref{section:logicalExpansion}).\\
---
> Logical expansion is defined by describing it wrt. the built-in predicate \code{phrase/3}   
> (see \ref{section:logicalExpansion} and \ref{sssection:phraseSpecification})
856a845,847
> Execution of this predicate serves two goals: Firstly the final expansion(of a grammar rule) (cf. definition 3.6),
> when this has not taken place earlier, i.e. preparation for execution of its body and arguments; 
> thereafter, secondly, the execution of the resulting Prolog goals. \\
857a849,852
> \medskip
> \noindent
> From the parsing viewpoint \code{phrase(NT, S)} is  true when the terminal sequence \code{S} is covered (cf. Definition 3.4) by the non-terminal \code{NT}. Or, from the generation viewpoint it is true when
> \code{NT} generates \code{S}.
860c855,858
< Subclause \ref{section:logicalExpansion}, "Prolog Definition of phrase/3",  provides a reference implementation that further defines the semantics of expansion.\\
---
> Section \ref{section:logicalExpansion}, "Prolog Definition of Phrase/3",  provides a reference implementation that further defines the semantics of expansion.\\
> \noindent
> The numbering of the Prolog clauses of the procedure \code{dcg\_cbody/4} for the grammar control constructs of this section 10, starting with \%071\%, 
> is partially synchronized with the following subsection numbers.
863c861
< The following subclauses explicate the linkages between the terminal sequences upon expansion of the control constructs.
---
> In particular this subsection explicates the linkages between the terminal sequences upon expansion of the control constructs.
870c868
< In \code{phrase([ ], S0, S)} the expansion result of the grammar control construct \code{empty terminal sequence} 
---
> The expansion result of the grammar control construct \code{empty terminal sequence} 
872c870
< remaining terminal sequence \code{S} with the comprehensive terminal sequence \code{S0},
---
> remaining terminal sequence with the comprehensive terminal sequence,
873a872,873
> For a formal description of expansion of this form see section \ref{section:logicalExpansion}, clause \%071\%.
> 
879a880
> For a formal description of expansion of this form see section \ref{section:logicalExpansion}, clause \%072\%.
885c886
< In the body of a grammar-rule the non-terminal \code{(',')//2} acts as principal functor of a \code{grammar-body-sequence} (cf. Definition 3.11) 
---
> In the body of a grammar-rule the non-terminal \code{(',')//2} acts as principal functor of a \code{grammar-body-sequence} (cf. Definition 3.12) 
888c889,890
< a conjunction wrt. subclause 7.8.5 of ISO/IEC 13211-1 Prolog, which results from expansion of \code{(',')//2}. \\
---
> a conjunction wrt. section 7.8.5 of ISO/IEC 13211-1 Prolog, which results from expansion of \code{(',')//2}. \\
> For a formal description of expansion of this form see section \ref{section:logicalExpansion}, clause \%073\%.
893c895
< expanded grammar-rule-head and a semicontext;
---
> expanded grammar-rule-head and a right-hand-context;
900,901c902,903
< In the body of a grammar rule \code{(;)//2} acts as principal functor of a \\ \code{alternative}. (cf. Definition 3.1) with a first grammar body GBFirst and a second grammar body GBSecond. 
< Each of them is subject to subsequent separate expansion - GBFirst first, and then GBSecond. The alternative is expanded to the disjunction \code{(;)/2} wrt. subclause 7.8.6 of ISO/IEC 13211-1 Prolog. 
---
> In the body of a grammar rule \code{(;)//2} acts as principal functor of a \\ \code{grammar-body-alternative}. (cf. definition 3.8) with a first grammar body GBFirst and a second grammar body GBSecond. 
> Each of them is subject to subsequent separate expansion - GBFirst first, and then GBSecond. The grammar-body-alternative is expanded to the disjunction \code{(;)/2} wrt. section 7.8.6 of ISO/IEC 13211-1 Prolog. 
902a905
> For a formal description of expansion of this form see section \ref{section:logicalExpansion}, clause \%074\%.
906c909
< NOTE  ---  The effect of comma and semicolon, \code{(',')//2}, \code{(;)//2}, may be understood best by application of \code{write\_canonical/1} (see subclause 8.14.2.5 of ISO/IEC 13211--1) on a grammar rule, containing them:\\
---
> NOTE  ---  The effect of comma and semicolon, \code{(',')//2}, \code{(;)//2}, may be understood best by application of \code{write\_canonical/1} (see section 8.14.2.5 of ISO/IEC 13211--1) on a grammar rule, containing them:\\
931,942d933
< \end{verbatim}
< \end{quote}
< 
< \subsubsection{\code{->//2} -- if-then-else}
< 
< \label{sssection:ifThenElse}
< 
< \noindent
< \code{(;)//2} (cf. \ref{sssection:alternative}) serves two different functions depending on whether or not its first argument is a compound term
< with functor \code{(->)//2}.\
< See \ref{sssection:alternative} for the use of \code{(;)//2} for \code{alternative}, when
< the first argument of \code{(;)//2} is not a  \code{(->)//2}.\
944,949d934
< \vspace{1em}
< \noindent
< The grammar control construct \code{(;)//2} has as arguments a grammar body GBFirst and a second grammar body GBSecond. 
< If the principal functor of GBFirst is \code{(->)//2} with arguments GBIf and GBThen, then the
< grammar rule bodies GBIf, GBThen, and GBSecond are subject to separate expansion to 
< GBIfExpanded, GBThenExpanded and GBSecondExpanded, respectively.\\ 
951,965c936,937
< \medskip
< \noindent
< The result of expansion is an if-then-else 
< (cf subclause 7.8.8 of ISO/IEC 13211-1), resulting from expansion of \code{(;)//2}, \\
< with the if-then construct \code{->(GBIfExpanded, GBThenExpanded)} as first, 
< and \code{GBSecondExpanded} as second argument.
< 
< \medskip
< \noindent
< 
< \begin{comment}
< \medskip
< \noindent
< There shall be no use of \code{(->)//2} in grammar rules except in the first argument of an alternative as described above. 
< \end{comment}
---
> \end{verbatim}
> \end{quote}
970c942
< for an alternative. See subclause \ref{sssection:alternative}.
---
> for a grammar-body-alternative. See subsection \ref{sssection:alternative}.
976,978c948
< used for "if-then-else", as \code{('|')//2} shall not be used for "if-then-else". See subclause \ref{sssection:ifThenElse}.
< 
< \subsubsection{\code{\{\}//1} -- grammar-body-goal}
---
> used for "if-then-else", as \code{('|')//2} shall not be used for "if-then-else". See subsection \ref{sssection:ifThenElse}.
982,985c952
< The non-terminal \code{\{G\}}, with \code{G} a Prolog goal, according to ISO/IEC 13211-1:1995, can stand at any place of a non-terminal inside a grammar-rule-body. After expansion the 
< braces are omitted, the goal G is unchanged. On execution G is executed like any Prolog goal. \\
< \noindent
< If {G} immediately contains a cut ('!'), this is handled like a grammar-body-cut (cf. \ref{ssection:grammarCut}).
---
> For a formal description of expansion of this form see section \ref{section:logicalExpansion}, clause \%075\%.
1009a977,979
> \medskip
> \noindent
> For a formal description of expansion of \code{call//1} see section \ref{section:logicalExpansion}, clause \%076\%.
1031,1032d1000
<  
< \subsubsection{\code{phrase//1}}
1034c1002
< % modified JPEH
---
> \subsubsection{\code{\{\}//1} -- grammar-body-goal}
1036,1041d1003
< \noindent
< \code{phrase//1} is a grammar-built-in predicate for using the built-in predicate \code{phrase/3}.
<  
< \medskip
< \noindent 
< Expanding, i.e. preparing for execution of the non-terminal 
1043a1006,1014
> \noindent
> The non-terminal \code{\{G\}}, with \code{G} a Prolog goal, according to ISO/IEC 13211-1:1995, can stand at any place of a non-terminal inside a grammar-rule-body. After expansion the 
> braces are omitted, the goal G is unchanged. On execution G is executed like any Prolog goal. \\
> \noindent
> If {G} immediately contains a cut ('!'), this is handled like a grammar-body-cut (cf. \ref{ssection:grammarCut}). \\
> \noindent
> For a formal description of expansion of \code{(\{G\}//1} see section \ref{section:logicalExpansion}, clause \%077\%.
>   
> \subsubsection{\code{($\backslash$+)//1} -- grammar-body-not}
1045,1047d1015
< \code{phrase//1} 
< 
< \medskip
1049,1051c1017,1019
< with argument 
<  
< \medskip
---
> In the body of a grammar rule \code{($\backslash$+)//1} is expanded to the principal functor \code{($\backslash$+)/1} of a \code{grammar-body-not} (cf. Definition 3.11)
> This functor \code{($\backslash$+)/1} is applied to the expanded argument of the
> \code{grammar-body-not}. If the resulting goal succeeds the expanded rule does not change the comprehensive terminal sequence.\\
1053c1021,1022
< \code{G}  
---
> \noindent
> For a formal description of expansion of \code{($\backslash$+)//1} see section \ref{section:logicalExpansion}, clause \%078\%.
1057c1026
< shall result in a goal for the built-in predicate 
---
> Implementations conforming to this TR shall not define or use a predicate \code{($\backslash$+)/3}.  \\
1059d1027
< \medskip
1061,1063d1028
< \code{phrase/3}
<  
< \medskip
1065c1030
<  with first argument \code{G}.
---
> NOTE  ---  The effect of \code{($\backslash$+)//1}  can be seen in the following example.\\ 
1067d1031
< \medskip
1069c1033,1048
< For a definition of the built-in predicate \code{phrase/3} see subclause \ref{sssection:phraseSpecification}.\\
---
> The grammar rule 
> 
> \begin{quote}
> \begin{verbatim}
> a --> \+ b.
> \end{verbatim}
> \end{quote}
> 
> \noindent
> may be expanded to:
> 
> \begin{quote}
> \begin{verbatim}
> a(S0, S) :- \+ b(S0, _), S0 = S.
> \end{verbatim}
> \end{quote}
1075c1054
< In the body of a grammar rule \code{!//0} is  a \code{grammar-body-cut}. After expansion the grammar-body-cut becomes the control construct cut, \code{!/0}, as in subclause 7.8.4 of ISO/IEC 13211-1 Prolog.\
---
> In the body of a grammar rule \code{!//0} is  a \code{grammar-body-cut}. After expansion the grammar-body-cut becomes the control construct cut, \code{!/0}, as in section 7.8.4 of ISO/IEC 13211-1 Prolog.\
1076a1056
> For a formal description of expansion of \code{!//0}  see section \ref{section:logicalExpansion}, clause \%079\%.
1082c1062,1064
< \subsubsection{\code{($\backslash$+)//1} -- grammar-body-not}
---
> \subsubsection{\code{(;)//2} and \code{->//2} -- if-then-else}
> 
> \label{sssection:ifThenElse}
1085,1087c1067,1070
< In the body of a grammar rule \code{($\backslash$+)//1} is expanded to the principal functor \code{($\backslash$+)/1} of a \code{grammar-body-not} (cf. Definition 3.10)
< This functor \code{($\backslash$+)/1} is applied to the expanded argument of the
< \code{grammar-body-not}. If the resulting goal succeeds the expanded rule does not change the comprehensive terminal sequence.\\
---
> \code{(;)//2} serves two different functions depending on whether or not its first argument is a compound term
> with functor \code{(->)/2}.\
> See \ref{sssection:alternative} for the use of \code{(;)//2} for \code{alternative}, when
> the first argument of \code{(;)//2} is not a  \code{(->)/2}.\
1089,1091c1072,1084
< %\noindent
< %For a formal description of expansion of \code{($\backslash$+)//1} see subclause \ref{section:logicalExpansion}, clause \%078\%.
< % omit JPEH 
---
> \vspace{1em}
> \noindent
> The grammar control construct \code{(;)//2} shall have as arguments a grammar body GBFirst and a second grammar body GBSecond. 
> The principal functor of GBFirst is \code{(->)/2} with arguments GBIf and GBThen. In this if-then-else form the
> grammar rule bodies GBIf, GBThen, and GBSecond are subject to
> separate expansion to GBIfExpanded, GBThenExpanded and GBSecondExpanded, respectively.\\ 
> \medskip
> 
> The result of expansion is an if-then-else \code{(;)/2} 
> (cf section 7.8.8 of ISO/IEC 13211-1), resulting from expansion 
> of \code{(;)//2}, with the if-then construct
>  \code{->(GBIfExpanded, GBThenExpanded)} as first, 
> and \code{GBSecondExpanded} as second argument.
1095c1088
< Implementations conforming to this TR shall not define or use a predicate \code{($\backslash$+)/3}.  \\
---
> For a formal description of expansion of if-then-else see section \ref{section:logicalExpansion}, clause \%074\% and \%0710\%.
1096a1090,1096
> \begin{comment}
> \medskip
> \noindent
> There shall be no use of \code{(->)//2} in grammar rules except in the first argument of an alternative as described above. 
> \end{comment}
> 
> \subsubsection{\code{phrase//1}}
1099c1099,1106
< NOTE  ---  The effect of \code{($\backslash$+)//1}  can be seen in the following example.\\ 
---
> \code{phrase//1} is not included in the allowed constructs of the body (of a grammar-rule). It is designed
> as grammar-built-in predicate for using the built-in predicate \code{phrase/3}.
>  
> Expanding, i.e. preparing for execution of the non-terminal 
> 
> \medskip
> 
> \code{phrase//1} 
1100a1108
> \medskip
1102c1110,1112
< The grammar rule 
---
> with argument 
>  
> \medskip
1104,1108c1114
< \begin{quote}
< \begin{verbatim}
< a --> \+ b.
< \end{verbatim}
< \end{quote}
---
> \code{G}  
1109a1116
> \medskip
1111c1118
< may be expanded to:
---
> shall result in a goal for the built-in predicate 
1113,1117c1120,1132
< \begin{quote}
< \begin{verbatim}
< a(S0, S) :- \+ b(S0, _), S0 = S.
< \end{verbatim}
< \end{quote}
---
> \medskip
> 
> \code{phrase/3}
>  
> \medskip
> \noindent
>  with first argument \code{G}.
> 
> \medskip
> \noindent
> For a definition of the built-in predicate \code{phrase/3} see section \ref{sssection:phraseSpecification}.\\
> 
> \medskip
1134,1135c1149,1150
< as specified in subclause 7.7.7 of ISO/IEC 13211--1, then the error term as specified 
< in subclause 7.7.7b of ISO/IEC 13211--1 when the flag \code{unknown} is set to \code{error} 
---
> as specified in section 7.7.7 of ISO/IEC 13211--1, then the error term as specified 
> in section 7.7.7b of ISO/IEC 13211--1 when the flag \code{unknown} is set to \code{error} 
1164c1179
< 2\hspace{1.5em}Parsing resp. generating of terminal sequences using grammar rules is defined in subclause \ref{sssection:phraseSpecification}. Grammar rules are expanded there into Prolog clauses during preparation for execution, which maps the parsing or generating with a grammar-rule-body into executing a goal given a sequence of predicate clauses. See subclause 7.7 of ISO/IEC 13211--1 for details.
---
> 2\hspace{1.5em}Parsing resp. generating of terminal sequences using grammar rules is defined in subsection \ref{sssection:phraseSpecification}. Grammar rules are expanded there into Prolog clauses during preparation for execution, which maps the parsing or generating with a grammar-rule-body into executing a goal given a sequence of predicate clauses. See section 7.7 of ISO/IEC 13211--1 for details.
1183,1189c1198
< \code{phrase(GRBody, S0, S)}  is true iff  \code{S0} either unifies with the concatenation of the grammar-body-sequence of \code{GRBody}, if any, (cf. Definition 3.11) with the remaining terminal-sequence \code{S}, or with the concatenation of a terminal-sequence resulting from generation by the non-terminal, if any, of \code{GRBody} w.r.t. the current Grammar rules with the remaining terminal-sequence \code{S}.\\
< 
< \medskip
< \noindent
< Execution of the predicate \code{phrase/3} serves two goals: Firstly the final expansion(of a grammar rule) (cf. Definition 3.7),
< when this has not taken place earlier, i.e. preparation for execution of its body and arguments; 
< thereafter, secondly, the execution of the resulting Prolog goals. \\
---
> \code{phrase(GRBody, S0, S)}  is true iff  \code{S0} either unifies with the concatenation of the grammar-body-sequence of \code{GRBody}, if any, (cf. Definition 3.12) with the remaining terminal-sequence \code{S}, or with the concatenation of a terminal-sequence resulting from generation by the non-terminal, if any, of \code{GRBody} w.r.t. the current Grammar rules with the remaining terminal-sequence \code{S}.\\
1196c1205
< NOTE 2 ---	The simple grammar of example 7.14.1.1 may be prepared here for execution.\\
---
> NOTE 2 ---	The simple grammar of example 7.14.1.1 may be prepared for execution.\\
1197a1207
> \medskip
1208a1219
> \medskip
1210c1221
< \code{phrase(noun\_phrase, [the, dog, barks], [barks])} is true.\
---
> \code{phrase(noun\_phrase, [the, dog, barks], [barks])} is true.\\
1214c1225
< If the non-terminal of \code{GRBody}, if any, is followed by a semicontext (cf. Definition 3.21), then the semicontext shall be prefixed to the remaining terminal sequence after having been parsed resp. generated wrt. the non-terminal of \code{GRBody}.\\
---
> If the non-terminal of \code{GRBody}, if any, is followed by a right-hand-context (cf. Definition 3.23), then the right-hand-context shall be prefixed to the remaining terminal sequence after having been parsed resp. generated wrt. the non-terminal of \code{GRBody}.\\
1216c1227
< Procedurally, \code{phrase(GRBody, S0, S)} is executed by calling the Prolog goal corresponding to the expansion of the grammar-rule-body \code{GRBody}, given the terminal-sequences \code{S0} and \code{S}, according to the logical expansion of grammar rules described in subclause \ref{section:logicalExpansion}. See in particular the clauses for \code{dcg\_rule/4}.\\
---
> Procedurally, \code{phrase(GRBody, S0, S)} is executed by calling the Prolog goal corresponding to the expansion of the grammar-rule-body \code{GRBody}, given the terminal-sequences \code{S0} and \code{S}, according to the logical expansion of grammar rules described in section \ref{section:logicalExpansion}. See in particular the clauses for \code{dcg\_rule/4}.\\
1219c1230
< \code{phrase(GRBody, S0, S)} shall be steadfast (cf. 3.22) in its third argument S. 
---
> \code{phrase(GRBody, S0, S)} shall be steadfast  in  its third argument S (cf. Definition 3.24).
1260d1270
< 
1302d1311
< \noindent
1304d1312
< 
1307a1316
> 
1310a1320
> 
1311a1322
>  | ?- phrase(sentence, [the, girl, likes, the, boy, today]).
1313d1323
< | ?- phrase(sentence, [the, girl, likes, the, boy, today]).
1316c1326,1327
< | ?- phrase(sentence, [the, girl, likes]). 
---
> | ?- phrase(sentence, [the, girl, likes]).
>  
1327a1339
> 
1328a1341
> 
1330a1344
> 
1360c1374
< NOTE --- The predicate \code{term\_expansion/2} is described in subclause \ref{sssection:termExpansion}.
---
> NOTE --- The predicate \code{term\_expansion/2} is described in subsection \ref{sssection:termExpansion}.
1498,1499d1511
< % JPEH I changed the reference numbers to match the subclauses.
< 
1501,1502c1513,1516
< % To avoid name clashes, if there exists already a phrase/3 in the processor: 
< % the functor "phrase/3" may be replaced by "iso_phrase/3" or else.
---
> % To avoid name clashes: if phrase/3 exists already on the processor, 
> % the word "phrase" may be replaced by "iso_phrase" or else at two places.
> % Missing prerequisite definitions as append/3 shall be defined by
> % the "Prolog Prologue" (ISO/IEC JTC1 SC22 WG17 N235)
1506,1507d1519
< % This program uses append/3 as defined in the "Prolog Prologue":
< % The "Prolog Prologue" is ISO/IEC JTC1 SC22 WG17 N235
1508a1521
> %01%
1513c1526,1528
< % Expands a DCG rule into a Prolog rule, when no error condition applies.
---
> %02%
> % dcg_rule(DCGrule, S0, S, Expansion).
> % Translates a DCG rule into a Prolog rule, when no error condition applies.
1515c1530
< dcg_rule(( NonTerminal, Terminals --> GRBody ), ( Head :- Body )) :-
---
> dcg_rule((NonTerminal, Terminals --> GRBody), S0, S, (Head :- Body)) :-
1519,1521c1534,1537
<    Body = ( Goal1, Goal2 ).
< dcg_rule(( NonTerminal --> GRBody ), ( Head :- Body )) :-
<    NonTerminal \= ( _, _ ),
---
>    Body = (Goal1, Goal2).
> 
> dcg_rule((NonTerminal --> GRBody), S0, S, (Head :- Body)) :-
>    NonTerminal \= (_,_),
1524a1541,1543
> %03%
> % translates a grammar goal non-terminal:
> 
1529a1549,1551
> %04%
> % translates a terminal-sequence:
> 
1532a1555,1557
> %05%
> % translates a grammar-rule-body:
> 
1535a1561
> 
1539a1566
> 
1543c1570
<    NonTerminal \= ( _ -> _ ),
---
>    NonTerminal \= (_->_),
1546,1559c1573,1582
< % The following constructs in a grammar rule body
< % are defined in the corresponding subclauses.
< 
< dcg_constr([]).          % 7.15.1
< dcg_constr([_|_]).       % 7.15.2 - terminal sequence
< dcg_constr(( _, _ )).    % 7.15.3 - concatenation
< dcg_constr(( _ ; _ )).   % 7.15.4 - alternative
<                          % 7.15.5 - if-then-else
< dcg_constr(( _ '|' _ )). % 7.15.6 - alternative
< dcg_constr({_}).         % 7.15.7
< dcg_constr(call(_)).     % 7.15.8
< dcg_constr(phrase(_)).   % 7.15.9
< dcg_constr(!).           % 7.15.10
< dcg_constr(\+ _).        % 7.15.11
---
> %06%
> dcg_constr([]).
> dcg_constr([_|_]).
> dcg_constr((_,_)).
> dcg_constr((_;_)).
> dcg_constr((_'|'_)).
> dcg_constr(call(_)).
> dcg_constr({_}).
> dcg_constr(\+_).
> dcg_constr(!).
1561,1562c1584,1585
< % The principal functor of the first argument indicates
< % the construct to be expanded.
---
> %071%
> dcg_cbody([], S0, S, (S0=S)).
1564c1587
< dcg_cbody([], S0, S, S0 = S ).
---
> %072%
1567c1590,1592
< dcg_cbody(( GRFirst, GRSecond ), S0, S, ( First, Second )) :-
---
> 
> %073%
> dcg_cbody(( GRFirst , GRSecond ), S0, S, ( First, Second )) :-
1569a1595,1596
> 
> %074%
1571,1572c1598,1599
<    \+ subsumes_term(( _ -> _ ),GREither),
<    dcg_body(GREither, S0, S, Either),
---
>    subsumes_term((_->_),GREither),
>    dcg_cbody(GREither, S0, S, Either),
1573a1601,1602
> 
> 
1575,1576c1604,1605
<    subsumes_term(( _ -> _ ),GREither),
<    dcg_cbody(GREither, S0, S, Either),
---
>    \+ subsumes_term((_->_),GREither),
>    dcg_body(GREither, S0, S, Either),
1577a1607,1608
> 
> %075%
1581c1612,1613
< dcg_cbody({Goal}, S0, S, ( Goal, S0 = S )).
---
> 
> %076%
1583,1584c1615,1620
< dcg_cbody(phrase(Body), S0, S, phrase(Body, S0, S)).
< dcg_cbody(\+ GRBody, S0, S, ( \+ Goal, S0 = S )) :-
---
> 
> %077%
> dcg_cbody({Goal}, S0, S, (Goal, S0 = S)).
> 
> %078%
> dcg_cbody(\+ GRBody, S0, S, (\+ Goal, S0 = S)) :-
1586c1622,1626
< dcg_cbody(!, S0, S, ( !, S0 = S )).
---
> 
> %079%
> dcg_cbody(!, S0, S, (!, S0 = S)).
> 
> %0710%
1589a1630
> 
1590a1632
>