TY - JOUR
T1 - Making a Productive Use of Failure to Generate Witnesses for Coinduction from Divergent proof Attempts
AU - Dennis, L.
AU - Bundy, Alan
AU - Green, I.
PY - 2000
Y1 - 2000
N2 - Coinduction is a proof rule. It is the dual of induction. It allows reasoning about non--well--founded structures such as lazy lists or streams and is of particular use for reasoning about equivalences. A central difficulty in the automation of coinductive proof is the choice of a relation (called a bisimulation). We present an automation of coinductive theorem proving. This automation is based on the idea of proof planning. Proof planning constructs the higher level steps in a proof, using knowledge of the general structure of a family of proofs and exploiting this knowledge to control the proof search. Part of proof planning involves the use of failure information to modify the plan by the use of a proof critic which exploits the information gained from the failed proof attempt. Our approach to the problem was to develop a strategy that makes an initial simple guess at a bisimulation and then uses generalisation techniques, motivated by a critic, to refine this guess, so that a larger class of coinductive problems can be automatically verified.The implementation of this strategy has focused on the use of coinduction to prove the equivalence of programs in a small lazy functional language which is similar to Haskell. We have developed a proof plan for coinduction and a critic associated with this proof plan. These have been implemented in CoCLAM, an extended version of CLAM with encouraging results. The planner has been successfully tested on a number of theorems.
AB - Coinduction is a proof rule. It is the dual of induction. It allows reasoning about non--well--founded structures such as lazy lists or streams and is of particular use for reasoning about equivalences. A central difficulty in the automation of coinductive proof is the choice of a relation (called a bisimulation). We present an automation of coinductive theorem proving. This automation is based on the idea of proof planning. Proof planning constructs the higher level steps in a proof, using knowledge of the general structure of a family of proofs and exploiting this knowledge to control the proof search. Part of proof planning involves the use of failure information to modify the plan by the use of a proof critic which exploits the information gained from the failed proof attempt. Our approach to the problem was to develop a strategy that makes an initial simple guess at a bisimulation and then uses generalisation techniques, motivated by a critic, to refine this guess, so that a larger class of coinductive problems can be automatically verified.The implementation of this strategy has focused on the use of coinduction to prove the equivalence of programs in a small lazy functional language which is similar to Haskell. We have developed a proof plan for coinduction and a critic associated with this proof plan. These have been implemented in CoCLAM, an extended version of CLAM with encouraging results. The planner has been successfully tested on a number of theorems.
U2 - 10.1023/A:1018940332714
DO - 10.1023/A:1018940332714
M3 - Article
VL - 29
SP - 99
EP - 138
JO - Annals of Mathematics and Artificial Intelligence
T2 - Annals of Mathematics and Artificial Intelligence
JF - Annals of Mathematics and Artificial Intelligence
SN - 1012-2443
IS - 1-4
ER -