The system is based on the equational superposition calculus. In contrast to most other current provers, the implementation actually uses a purely equational paradigm, and simulates non-equational inferences via appropriate equality inferences. Significant innovations include shared term rewriting (where many possible equational simplifications are carried out in a single operation), several efficient term indexing data structures for speeding up inferences, advanced inference literal selection strategies, and various uses of machine learning techniques to improve the search behaviour. Since version 2.0, E supports many-sorted logic.
E is implemented in C and portable to most UNIX variants and the Cygwin environment. It is available under the GNU GPL.
Competitions
The prover has consistently performed well in the CADE ATP System Competition, winning the CNF/MIX category in 2000 and finishing among the top systems ever since. In 2008 it came in second place. In 2009 it won second place in the FOF (full first order logic) and UEQ (unit equational logic) categories and third place (after two versions of Vampire) in CNF (clausal logic). It repeated the performance in FOF and CNF in 2010, and won a special award as "overall best" system. In the 2011 CASC-23 E won the CNF division and achieved second places in UEQ and LTB.
Applications
E has been integrated into several other theorem provers. It is, with Vampire, SPASS, CVC4, and Z3, at the core of Isabelle's Sledgehammer strategy. E also is the reasoning engine in SInE and LEO-II and used as the clausification system for iProver.
Applications of E include reasoning on large ontologies, software verification, and software certification.
References
↑Schulz, Stephan (2002). "E – A Brainiac Theorem Prover". Journal of AI Communications. 15 (2/3): 111–126.
↑Schulz, Stephan (2001). "Learning Search Control Knowledge for Equational Theorem Proving". KI 2001: Advances in Artificial Intelligence. Lecture Notes in Computer Science. Vol.2174. pp.320–334. doi:10.1007/3-540-45422-5_23. ISBN978-3-540-42612-7.
↑Meng, Jia; Lawrence C. Paulson (2004). Experiments on Supporting Interactive Proof Using Resolution. Lecture Notes in Computer Science. Vol.3097. Springer. pp.372–384. doi:10.1007/978-3-540-25984-8_28. ISBN978-3-540-22345-0.
↑Benzmüller, Christoph; Lawrence C. Paulson; Frank Theiss; Arnaud Fietzke (2008). "LEO-II – A Cooperative Automatic Theorem Prover for Classical Higher-Order Logic (System Description)". Automated Reasoning(PDF). Lecture Notes in Computer Science. Vol.5195. Springer. pp.162–170. doi:10.1007/978-3-540-71070-7_14. ISBN978-3-540-71069-1. Archived from the original(PDF) on 15 June 2011. Retrieved 20 December 2009.
↑Korovin, Konstantin (2008). "iProver—an instantiation-based theorem prover for first-order logic". Automated Reasoning. Lecture Notes in Computer Science. Vol.5195. pp.292–298. doi:10.1007/978-3-540-71070-7_24. ISBN978-3-540-71069-1.