- From: Steven Pemberton <steven.pemberton@cwi.nl>
- Date: Fri, 17 Dec 2021 20:19:24 +0000
- To: Dave Pawson <dave.pawson@gmail.com>, "C. M. Sperberg-McQueen" <cmsmcq@blackmesatech.com>
- Cc: "Norm Tovey-Walsh" <norm@saxonica.com>, ixml <public-ixml@w3.org>
> > - An alternative that matches no sequences at all, which no thing > > matches. This is an expression which denotes the language with > > no sentences, i.e. the empty set. And this is the meaning most > > naturally associated with the symbol “∅”. > > Any reason why [] should not be given this definition? It does have that definition, but that is a different definition to what you require. () matches the empty string, so always succeeds. [] matches *nothing at all*, so always fails. Steven
Received on Friday, 17 December 2021 20:19:44 UTC