|About finding the start symbol of a grammar firstname.lastname@example.org (Eduardo Costa) (2021-05-21)|
|Re: About finding the start symbol of a grammar email@example.com (Kaz Kylheku) (2021-05-21)|
|Re: About finding the start symbol of a grammar DrDiettrich1@netscape.net (Hans-Peter Diettrich) (2021-05-21)|
|Re: About finding the start symbol of a grammar firstname.lastname@example.org (2021-05-21)|
|Re: About finding the start symbol of a grammar email@example.com (Ev. Drikos) (2021-05-22)|
|Re: About finding the start symbol of a grammar firstname.lastname@example.org (gah4) (2021-05-22)|
|From:||"Ev. Drikos" <email@example.com>|
|Date:||Sat, 22 May 2021 06:52:17 +0300|
|Organization:||Aioe.org NNTP Server|
|Injection-Info:||gal.iecc.com; posting-host="news.iecc.com:2001:470:1f07:1126:0:676f:7373:6970"; logging-data="33346"; mail-complaints-to="firstname.lastname@example.org"|
|Posted-Date:||22 May 2021 13:23:54 EDT|
On 21/05/2021 13:49, Eduardo Costa wrote:
> While there would exist grammars we could recursively check to find out which
> it's start symbol is (i.e.: it's the only rule that used the rest of them,
> where checking every other resulted in dangling rules that weren't even called
> in), there might be other grammars for which more than one rule yields full
> coverage (all of these obviously defining different languages) and so leading
> to ambiguity.
IMHO, it can be so simple as you describe here without important overhead.
Typically, a parser will reduce the start symbol and finish. All rules
that yield full coverage can be ie alternatives of a single root symbol:
RootSymbol -> R1 | R2 | ... | Rn
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