Re: Action-931 EBNF in PRD, Appendix 9

Stella,

Stella Mitchell <stellamit@gmail.com> wrote on 24/10/2009 03:14:00:
> 
> Harold mentioned that he thinks "External" should be mandatory in the
> PRD PS syntax, for maximum compatibility between PRD and BLD.

It would just make the PS (even) more difficult to read, but I would not 
object, if it was deemed useful or necessary.

> Axel mentioned that Name, Var, and SYMSPACE in the PRD EBNF could be
> brought in line with the current FLD/BLD/DTB versions of those
> productions.

I corrected Var and Name. I did not find a difference for SYMSPACE, but I 
copied the production from BLD nonetheless :-)

>    --  it looks like there's an erroneous "'Expr'" in the GROUNDTERM
> production of the condition language.

Right. Corrected.

>    --  In the RULE production
>             ' such that '  FORMULA*
>                    should be changed to
>             ('such that '  FORMULA)*  ?

Rather ('such that ' FORMULA+)?

Corrected.

>    -- how do the last three options in the ACTION_BLOCK production
> relate to what is described in Section 3.1.2 -  are they an Assert,
> Modify, Retract or Execute?  This syntax (the EBNF version) is used in
> the test cases.

See 8.4.2. A note to the same effect could be added in 3.1.2, if deemed 
useful o rnecessary.

>    --  based on section 3.1.2, I think in the ACTION_BLOCK production,
>              Var (Frame | 'New()'))*
>                  should be changed to
>              ( '('  Var ( Frame | 'New()'  ')'  )*

Corrected.

>    --  the PS version of test case [1] is not valid according to the
> Appendix 9 EBNF because a membership formula (ex:o#ex:T) is not a
> valid action_block.
> [1] http://www.w3.org/2005/rules/wiki/Conflict_resolution

Yes, that test case would give the expected conclusion if ex:o#ex:T and 
ex:o[ex:p->1] where imported.

Another way to write the test case without that problem is with a 
well-formed action block
Do((?x New()) ?x#ex:T ?x[ex:p->1])

The problem is, then, that the conclusion is an existential formula.

I would just leave it as it is, possibly clarifying that the facts base 
must be initialized with the two facts.

>    -- Core test cases are also PRD test cases but the PS versions of
> them are not PRD PS because of ":-" instead of "IF...THEN,"  I don't
> know if this is a problem (for readability for PRD audience)

We can add that possibility in the EBNF, if deemed useful or necessary.

Cheers,

Christian

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