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	id AA15790; Mon, 8 Apr 91 18:37:31 -0700
From: cbmvax!uunet!m2xenix!onion!tessi!loop!dont (Don Taylor)
Message-Id: <9104090137.AA15790@loop.UUCP>
Date: Mon,  8 Apr 91 18:37:28 PDT
To: lojban-list@snark.thyrsus.com
Cc: dont
Subject: Uncertainties in EBNF Notation
Status: RO
X-From-Space-Date: Wed Apr 10 01:29:51 1991
X-From-Space-Address: cbmvax!uunet!m2xenix!onion!tessi!loop!dont


I sent this to lojbab and he suggested I post it here.

I just received the ju'i lobypli mailing with the lojban machine grammar in
ebnf notation.  It seems that the notation is ambiguous in that no precedence
is specified for the notation.  For example

	indicators&free...

may denote

	(indicators&free)...
or
	indicators&(free...)

etc.  Many of the other ebnf operators are open to the same interpretation.
I would greatly appreciate a more precise definition of precedence, and
associativity if relevant.

Item 10, "// encloses an elidable terminator, which may be omitted (without
change of meaning) if no grammatical ambiguity results" disturbs me.  Reading
bnf as a definition of a language, which I take as the definition of what
is grammatical and what is not, leaves me uncertain of how to interpret the
document.

Thanks
Don Taylor
503-644-7631
loop!dont@tessi.UUCP
dont@loop.UUCP
tessi!loop!dont@nosun.west.sun.com