[lojban] Computer grammar question: non-left recursive RPN?

[Robin Lee Powell <lojban-out@lojban.org>]

Lojban has a reverse polish (i.e. postfix math) mode built in.

The ABNF form of this rule is:

rp-expression = rp-operand rp-operand operator

rp-operand = operand / rp-expression

which does exactly what you'd expect.

I can't figure out a way to convert this into a version without left
recursion.  I've got:

rp-expression = operand rp-expression-tail
rp-expression-tail = rp-expression operator rp-expression-tail / ()

(where () is the empty production), but I'm not at all certain it's
equivalent, and the parse trees it produces look very wrong (i.e.
not left recursive at all).

Help?

-Robin

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