RE: [xml-dev] Large class of problems: constrain a bunch of piecesto for

Hi Mike,

Yes, this is an example of DAG with A as a source and C as a sink.

I think the rules also do allow "A -> B -> C -> B -> D", which is an example of graph with a cycle but still a single source (A) and sink (D), which is not forbidden by the rules. Or am I missing something?

The rules even seem to allow for several connected components with additional self-contained loops, like

(start: A, end: C)

A -> B

B -> C

D -> E

E -> D

If such is the case, we are forward compatible with the 23rd century. Beam me up, Scotty! :-)

Kind regards,

Ghislain

From: Michael Kay [mike@saxonica.com]
Sent: Monday, February 20, 2017 6:20 PM
To: Costello, Roger L.
Cc: xml-dev@lists.xml.org
Subject: Re: [xml-dev] Large class of problems: constrain a bunch of pieces to form a chain

I think those conditions are satisfied by

r.start = A

r.end = C

s1.start = A

s1.end = B

s2.start = B

s2.end = C

s3.start = A

s3.end = C

and I don't think you had that in mind as a valid route (a "single connected chain"). Perhaps your "or" in rules (1) and (2) should be an "exclusive or".

I don't know whether you consider something like A -> B -> C -> B -> D as a valid route. I don't know whether any planes fly such routes but I've certainly been on country bus journeys that followed that pattern. If such routes are legal you may need to revise your rules.