Re: Draft iXML minutes, 4 March 2025

Bethan: One of the things I've been thinking about recently is that we have a bunch of dynamic errors that are things like there not being a single root node, or two attributes with the same name on the same element.
… Earlier the spec says that conformance is about processors and grammars, not the combination of a grammar and in input.
… That being the case, I think these should be static errors on the grammar; not errors that are only thrown if a particular input produces not-well formed XML.
… I'm convinced you can do it.


Real-life example: I have an input where repeatedly I get A, B and C, but not necessarily in that order.
I know the input is correct, so I write:


 input: event*.
 event: (A; B; C)+, #a.
 @a: date.
 @b: who.
 @c: where.
 date: ... etc


This grammar allows <event a="..." a="..."/>, but it will never happen because my input will never generate it.


If this were to be classed as a static error, then I would have to write:


 input: event*.
 event: (ABC; ACB; BAC; BCA; CAB; CBA), #a.
 ABC: a, b, c.
 ACB: a, c, b.
 BAC: b, a, c.
 BCA: b, c, a.
 CAB: c, a, b.
 CBA: c, b, a.
 @a: date.
 @b: who.
 @c: where.
 date: ... etc


which I would rather not have to do.


Steven

On Tuesday 18 March 2025 13:50:26 (+01:00), Steven Pemberton wrote:


Looks like you had a great discussion in the status reports section. Sorry I missed it.


Bethan says: "What I'm interested in working on are tools that will treat your grammar as a generator rather than a recognizer."


I've written several of these in the past (for instance, when I wrote a version of Eliza, the Rogerian psychotherapist, I wrote another program to generate random paranoid ramblings for Eliza to respond to (https://cwi.nl/~steven/Talks/2024/09-oxford/ai.html#L2734)


In fact, they are quite easy to write, since it is just a recursive random path through the grammar tree. This is the complete code, where 'thing' is either a terminal or nonterminal ('choice' returns a random element of a sequence, in this case returning a random alternative from a rule):


HOW TO GENERATE thing 
FROM grammar:
    SELECT:
        
nonterminal(thing):
            FOR symbol 
IN choice grammar[thing]:
            
    GENERATE symbol FROM grammar
        
ELSE:
            WRITE thing, " 
"


And you generate one rambling with "GENERATE '<sentence>' FROM sentences"


Steven


On Tuesday 04 March 2025 16:42:47 (+01:00), Norm Tovey-Walsh wrote:



> Hi folks,

>

> Draft minutes are online:

>

> https://www.w3.org/2025/03/04-ixml-minutes.html

>

> Be seeing you,

> norm

>

> --

> Norm Tovey-Walsh

> Saxonica

>

>