5.0.0

[cprudhom]

5.0.0 - 02 Feb 2026

Major features:

This set of commits delivers a major consolidation of Lazy Clause Generation, significant performance and memory improvements,
more robust constraint handling, and a broad cleanup and modernization of the internal APIs and tooling.

Performance & Algorithms

• Significant performance improvements on:
• Core propagators (X+Y=Z, abs, div, sum, scalar, etc.)
• CompactTable (CT) and STR2+
• Memory management and estimation mechanisms
• Dynamic selection of table algorithms based on memory footprint
• Optimizations in MiniSat and SAT-related components (clause reduction, propagation, assertions)

Lazy Clause Generation (LCG)

• Major consolidation effort on LCG:
• Fixes for critical bugs (initialization, reification, lost propagations)
• New assertions and invariants
• Improved separation and handling of learnt clauses (failure vs prohibiting-solution)
• Extended LCG support for constraints such as abs, div, table, element
• Better interaction with:
  • Restart strategies
  • ParallelPortfolio
  • Explanation and Reason APIs

Constraints & Modeling

• Refactoring or improvement of many constraints:
• AllDifferent, AllDifferentExcept*
• Cumulative, DiffN, BinPacking, Element, Table
• Arithmetic constraints (abs, div, times, min/max)
• Smarter choice between decomposition and extension
• Improved expression recognition and handling (XCSP / Flatzinc)

Testing & Robustness

• Numerous test fixes and stabilizations
• Addition of new tests, especially for LCG and XCSP
• Timeout adjustments
• Cleanup of memory-intensive or unstable tests

XCSP / Flatzinc / Parsing

• Update of XCSP3 tools (v2.5)
• Improvements in parsing and expression handling
• Better support for:
  • Negative values
  • Constants
  • Variable groups and restarts
• Competition-oriented adjustments for XCSP and Flatzinc

Search & Strategies

• Enhancements to:
  • RoundRobin strategies
  • Dom/Wdeg and ConflictHistorySearch
  • MetaStrategy framework
• New parameters and more robust default behaviors
• Simplification and clarification of search-related APIs

Refactoring & API Evolution

• Large-scale code cleanup:
  • Removal of obsolete classes
  • Simplification of core APIs (IntVar, Decision, Reason)
• Improved and updated Javadoc
• Clearer separation of responsibilities between Solver, MiniSat, and learning components

Build, CI & Tooling

• Updates to Maven configuration, Docker, and Makefiles
• CI workflow adjustments (tests, snapshots, releases)
• Preparation of intermediate and beta releases

Deprecated API (to be removed in next release):

Other closed issues and pull requests:

See milestone 5.0.0

• Performance improvement in PropXPlusYEqZ and PropAbsolute
• Fix bug in ConflictOrderingSearch (monitor not plugged)
• Performance improvement for LastConflict, ConflictOrderingSearch and StrategySequencer.
• Fix bug : regular constraints parsed from XCSP now support negative values
• Fix bug : Unexpected behavior when using Task with scalar ([BUG]Unexpected behavior when using Task with scalar #1114)
• Replace Cumulative implementation by state-of-the-art implementation of TimeTabling and OverloadChecking
• Fix bug : IntVar no longer extends Iterable to avoid errors in nested loops
• Fix bug : Fix iterator issue when using ISet, especially within graph variables ([BUG] InvalidSolutionException on UndirectedGraphVar #1174 and [BUG] Nested calls to ISetIterator go to unexpected behavior #1175)

Contributors to this release:

• Charles Prud'homme (@cprudhom)
• Jean-Guillaume Fages (@jgFages)
• Arthur Godet (@ArthurGodet)
• Sulian Le Bozec Chiffoleau (@SulianLBC)

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This discussion was created from the release 5.0.0.