1. Applications of Propositional Reasoning Systems
CSE 473 – Autumn 2003

2. Testing Circuit Equivalence
Do two circuits compute the same function?
Circuit optimization
Is there input for which the two circuits compute different values? C C’
nand A B A B

3. Testing Circuit Equivalence
nand D E A B A B

4. Symbolic Model Checking
Any finite state machine is characterized by a transition function
CPU
Networking protocol
Wish to prove some invariant holds for any possible inputs
Bounded model checking: formula is sat iff invariant fails k steps in the future

5. The SAT Competition strikes back…
In Italia
What is a good SAT solver ?
One that participates !

6. The hidden face of the Italian coast!
Thanks to
LRI (Orsay, France)
DIST (Genoa, Italia)
522 cpu days (2 clusters, 2 phases)
34 solvers (4 incomplete), 993 benchmarks,
15 Athlon and 8 P4 2.4 Ghz 1Gb RAM

7. The competition: why? ?
Provide a (regular) picture of current state-of-the-art SAT solvers
“Measure” the progress each year
Motivate (again and again) the field!
Visibility
One (important) question last year :
Would submitters be able to made substantial progress in only one year?

8. The Benchmarks (industrial)
323 benchmarks, 45 series
Hard_eq_check (E. Goldberg) [16,1]
Addm (J. Kukula) [6, 1] Equivalence check of two randomly structured adders with multiple addends
Li-exam, test (R. Li) [12, 2] : formulated from unit covering problem of logic minimization of logic ircuit benchmark test4
Ferry, gripper, hanoi [24,3] : based on TSP (tunable satplan). A DIMACS generator for planing problems in PDDL format
'l2s‘ [11,1]: (V. Schuppan) Bounded model checking of Bwolen Yangs collection of benchmarks for SMV in conjunction with a method to convert liveness to safety. 
And a lot of E. Zarpas BMC formulae…

10. Complete Industrial
Industrial, Sat + Unsat

11. Complete handmade
HandMade, Sat + Unsat

12. Incomplete Random
Random, Sat

13. The solvers (5/8)
saturn (S. Prestwich) [IR]: Saturn performs local search in a space of partial truth assignments that are consistent under unit propagation. It is a DPLL procedure with depth-first search replaced by an incomplete form of backtracking (Incomplete Dynamic Backtracking). The difference between version 2 and version 1 is a form of conflict diagnosis: variables are selected for unassignment by analysing the causes of dead-ends during search.
satzilla (K. Leyton-Brown, E. Nudelman, G. Andrew, C. Gomes, J. McFadden, B. Selman, Y. Shoham) [CD, CD-HC] : Portfollio of algorithms: 2clseq, Limmat, JeruSat, OKsolver, Relsat, Sato, Satzrand, and Zchaff. Satzilla2 also contains eqsatz and Heerhugo. 