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Re: [engelang] Xorban: Termsets



On Fri, Sep 28, 2012 at 9:37 PM, Mike S. <maikxlx@gmail.com> wrote:
>
>> >> >>
>> >> >> formula := CCA | term formula | foretree formula | formula
>> >> >> aftertree
>> >> >> aftertree := HI | term aftertree | JA aftertree aftertree
>> >> >> foretree := HE | term foretree | JA foretree foretree
>> >> >> term := NA | LA formula | JA formula
>>
>> I do want to keep the formal grammar unambiguous though, so it will
>> need to be considerably more complex if we want to keep he/hi.
>
> I am not sure what you have in mind,

This: http://en.wikipedia.org/wiki/Formal_grammar
"Any particular sequence of production rules on the start symbol
yields a distinct string in the language. If there are multiple ways
of generating the same single string, the grammar is said to be
ambiguous."

How we may deal with that ambiguity is a different matter, but that
grammar is ambiguous by that definition.

> Terms in front of formulas and aftertrees would have to be cleared before
> anything else can happen, so I *think* that terms in front of foretrees are
> the only rub.  I assume that you have something in mind to somehow enforce
> that precedence in the formal grammar?  Do you know of a reason why we can't
> just specify a precedence rule?

Ignoring aftertrees for now, I think this *might* remove the foretree ambiguity:

formula := core-formula | closed-foretree-formula | open-foretree formula
closed-foretree-formula := closed-foretree formula | term
closed-foretree-formula
foretree := open-foretree | closed-foretree
closed-foretree := JA foretree foretree
open-foretree := HE | term open-foretree
core-formula := CCA | term core-formula
term := NA | LA formula | JA formula

Assuming that's unambiguous (and that it generates everything we want
it to generate), we now need to add HI in such a way that it doesn't
create ambiguities with parentheticals.

co ma'a xrxe