Francoise,
There is plenty of text in the LRM that describes solver failures. The most general is in section 18.3:
- If a solution exists, the constraint solver shall find it. The solver can fail only when the problem is over-constrained and there is no combination of random values that satisfy the constraints.
The LRM does not mention "timely manner" or too many trials (in fact, non-backtracking solvers can be built so the trials are irrelevant). From the LRM perspective, a solver failure is an inability to satisfy the constraints - as defined above.
Arturo
From: Francoise Martinolle [mailto:fm@cadence.com]
Sent: Tuesday, September 27, 2011 10:18 AM
To: Francoise Martinolle; Arturo Salz; Ryan, Ray; Gran, Alex; 'sv-ec@eda.org'
Subject: RE: soft constraint proposal
Arturo,
In the proposal, the description of solving 2 soft constraints is described as:
- Consider two soft constraints c1 and c2, such that c1 has higher priority than c2.
1. The constraint solver will first try to produce a solution satisfying both c1 and c2.
2. If it fails in (1) then it will try to produce a solution satisfying only c1.
3. If it fails in (2) then it will try to produce a solution satisfying only c2.
4. If it fails in (3) then it will discard both c1 and c2.
Can you please explain what it means for the solver to fail? When is it considered to fail? When there is a contradiction or the solver is unable to find
a solution in a timely manner after many trials?
Francoise
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