CaDiCaL 3.0 (Tool Paper)

Abstract

The propositional satisfiability (SAT) solver Kissat supports a relatively narrow feature set in favor of bare-metal performance and targeted improvements to core solving techniques, which helped it dominate the International SAT Competition since 2024. However, many applications rely on advanced SAT solver features such as incremental interaction schemes, finding direct consequences of assumed literals, or expressive proof logging that allows for real-time checking. This system description reports on how we successfully adapted Kissat’s award-winning techniques to the full-featured incremental SAT solver CaDiCaL, including clausal congruence closure, clausal equivalence sweeping, and bounded variable addition. The main challenge was to support efficient linear proof production with hints. We further extended CaDiCaL’s API to extract implied literals under assumptions and applied advanced deterministic scheduling of inprocessing based on the ticks metric for approximating cache line accesses. Experiments confirm the benefits of these efforts.