Again wit da AND and Repetitions

John Cowan cowan at
Thu May 13 22:40:36 BST 1999

roddey at wrote:

> What are the feelings of some folks who implemented SGML validators? If you had
> to start with that and add NtoM repetition on top of that, where would that have
> taken you? Or did SGML already provide both of these things? If so, what was the
> general architecture used in some common ones? Why is the sky blue?

IIRC the canonical way of doing (A & B & C) is to transform it
into (A | B | C)* and then do a post-check that each of A, B, C
appears exactly once.  As opposed to brute-force expansion into a

John Cowan		cowan at
	You tollerday donsk?  N.  You tolkatiff scowegian?  Nn.
	You spigotty anglease?  Nnn.  You phonio saxo?  Nnnn.
		Clear all so!  'Tis a Jute.... (Finnegans Wake 16.5)

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