Re: [xml-dev] Re: Schemas: Different Strokes From Different Folks
From: John Cowan <johnwcowan@gmail.com>
To: "Henry S. Thompson" <ht@markup.co.uk>
Date: Wed, 18 Jan 2017 16:36:36 -0500
On Wed, Jan 18, 2017 at 4:17 PM, Henry S. Thompson <ht@markup.co.uk> wrote:
I understood Murata to have proved for RELAX NG that given two XML
languages, each (weakly) generated by a RELAX NG schema, the union _of
the languages_ would be generated by the union of the schemata.
Indeed, the proof is trivial. Let a be the root pattern of schema A, and b be the root pattern of schema B. Then <choice><ref name="a"/><ref name="b"/></choice> matches any document that matches either a or b or both. And since there are no constraints on the subpatterns of a choice pattern other than those inherited from the context of the choice pattern (which here is null), all such patterns are valid.
