Minor release
Minor release
General improvements:
Frontend
--<option name> instead of -<option name>.ae. .mlw and .why extension are still supported but depreciated.--input (resp --output) option to manually set the input (resp output) file format--err-formatter and --std-formatter options to set output formatters--pretty-output option to add better debug formatting and to add colors** in native Alt-Ergo syntax. The operator is fully interpreted when applied to constants--steps-count and improve the way steps are counted (AdaCore contribution)Reasoners:
Instantiation
--instantiation-heuristic option that can enable lighter or heavier instantiationBuild:
-static to configure for statically linked compilationOthers
--gc-policy to set the allocation policy of the garbage collectorMinor release:
Minor release:
General improvements:
Frontend:
Reasoners:
there are now 4 core solvers (default is cdcl-tableaux):
Instantiation:
Data structures:
Frontend:
Instantiation:
Reasoners:
SAT-solving:
Instantiation:
Frontend:
integration of floating-point arithmetic reasoning: this is done via the support of the rounding operator as done in the Gappa tool. FPA reasoning can be enabled by calling Alt-Ergo as follows:
alt-ergo -use-fpa -prelude fpa-theory-2017-01-04-16h00.why file.why
where fpa-theory-2017-01-04-16h00.why is a prelude distributed with Alt-Ergo. More details about the integration are given in this paper: https://hal.inria.fr/hal-01522770, and dditional benchmarks can be found here: https://gitlab.com/OCamlPro-Iguernlala/Three-Tier-FPA-Benchs
General Improvements:
** theories data structures: semantic values (internal theories representation of terms) are now hash-consed. This enables the use of hash-based comparison (instead of structural comparison) when possible
** theories combination: the dispatcher component, that sends literals assumed by the SAT solver to different theories depending on whether these literals are equalities, disequalities or inequalities, has been re-implemented. The new code is much simpler and enables new optimizations and factorizations
** case-split analysis: we made several improvements in the heuristics of the case-split analysis mechanism over finite domains
** explanations propagation: we improved explanations propagation in congruence closure and linear arithmetic algorithms. This makes the proofs faster thanks to a better back-jumping in the SAT solver part
** linear integer arithmetic: we re-implemented several parts of linear arithmetic and introduced important improvements in the Fourier-Motzkin algorithm to make it run on smaller sub-problems avoiding some redundant executions. These optimizations allowed a significant speed up on our internal benchmarks
** data structures: we optimized hash-consing and some functions in the "formula" and "literal" modules
** SAT solving: we made a lot of improvements to the default SAT-solver and to the SatML plugin. In particular, the decision procedure part now receives facts (literals) in bulk from the solvers, rather than individually, trimming the costs of intermediate calls to theories reasoners, such as Fourier-Motzkin
** Matching: we extended the E-matching algorithm to also perform matching modulo the theory of records. In addition, we simplified matching heuristics and optimized the E-matching process to avoid computing the same instances several times
** Memory management: thanks to the ocp-memprof tool (http://memprof.typerex.org/), we identified some parts of Alt-Ergo that needed some improvements in order to avoid useless memory allocations, and thus unburden the OCaml garbage collector
** the function that retrieves the used axioms and predicates (when option 'save-used-context' is set) has been improved
Bug Fixes:
** 6 in the "inequalities" module of linear arithmetic
** 4 in the "formula" module
** 3 in the "ty" module used for types representation and manipulation
** 2 in the "theories front-end" module that interacts with the SAT solvers
** 1 in the "congruence closure" algorithm
** 1 in "existential quantifiers elimination" module
** 1 in the "type-checker"
** 1 in the "AC theory" of associative and commutative function symbols
** 1 in the "union-find" module
New OCamlPro Plugins:
** profiling plugin: when activated, this plugin records and prints some information about the current execution of Alt-Ergo every 'n' seconds: In particular, one can observe a module being activated, a function being called, the amount of time spent in every module/function, the current decision/instantiation level, the number of decisions/instantiations that have been made so far, the number of case-splits, of boolean/theory conflicts, of assumptions in the decision procedure, of generated instances per axiom, ...
** fm-simplex plugin: when activated, this plugin is used instead of the Fourier-Motzkin method to infer bounds for linear integer arithmetic affine forms (which are used in the case-split analysis process). This module uses the Simplex algorithm to simulate particular runs of Fourier-Motzkin. In practice, the new algorithm scales better on linear integer arithmetic problems containing lots of inequalities
New Options:
-version-info: prints some information about this version of Alt-Ergo (release and compilation dates, release commit ID)
-no-theory: deactivate theory reasoning. In this case, only the SAT-solver and the matching parts are used
-inequalities-plugin: specify a plugin to use, instead of the "default" Fourier-Motzkin algorithm, to handle inequalities of linear arithmetic
-tighten-vars: when this option is set, the Fm-Simplex plugin will try to infer bounds for integer variables as well. Note that this option may be very expensive
-profiling-plugin: specify a profiling plugin to use to monitor an execution of Alt-Ergo
-profiling
-no-tcp: deactivate constraints propagation modulo theories
Removed Capabilities:
** the pruning module used in the frontend is not available anymore
** the SMT and SMT2 front-ends have been removed. We plan to implement a new front-end for SMT2 in upcoming releases
o the "SAT solving" part can now be delegated to an external plugin;
o new experimental SAT solver based on mini-SAT, provided as a plugin. This solver is, in general, more efficient on ground problems;
o heuristics simplification in the default SAT solver and in the matching (instantiation) module;
o re-implementation of internal literals representation;
o improvement of theories combination architecture;
o rewriting some parts of the formulas module;
o bugfixes in records and numbers modules;
o new option "-no-Ematching" to perform matching without equality reasoning (i.e. without considering "equivalence classes"). This option is very useful for benchmarks coming from Atelier-B;
o two new experimental options: "-save-used-context" and "-replay-used-context". When the goal is proved valid, the first option allows to save the names of useful axioms into a ".used" file. The second one is used to replay the proof using only the axioms listed in the corresponding ".used" file. Note that the replay may fail because of the absence of necessary ground terms generated by useless axioms (that are not included in .used file) during the initial run.
o Alt-Ergo is now maintained and distributed by OCamlPro, while academic research is conducted in partnership with the VALS team (LRI), o source code is reorganized into sub-directories, o quantifiers instantiation heuristics are simplified, o bug-fixes in matching, nums, records, sums, o improvement of the GUI when opening big files.
o bug fixes (existantial elimination, Euclidean division) o minor enhancement (transformation of boolean equalities into equivalences) o minor enhancement (sort axioms/definitions instances according to their size)
o new combination method for Shostak solvers
o improvement of non-linear multiplication distribution over addition
o input language extension: polymorphic declaration are now allowed (logic x: 'a)
o input language extension: the types of terms can now be forced in a formula using the construct <term> : <type> (see man for an example)
o input language modification: a label should be a string. The construct <label> : <term> is replaced by "<label>" : <term>
o new keywords in the syntax: inversion, check, cut and include
o experimental options for theories models generation:
-model option: model on labeled terms
-complete-model option: complete model
o -timelimit n option: set the time limit to n seconds (not supported on Windows)
o bug fixes o the number of instances for each axiom are now shown on the right of the GUI
o the number of instances of each axiom can be limited by the user
o the modifications made in the GUI can now be saved in a session file <f>.agr
o session files can be replayed with -replay option
o models can be displayed in the GUI
o unsat-cores (-proof option) can be used to simplify the contexto the theory of records replaces the theory of pairs o bug fixes (intervals, term data-structure, stack-overflows, matching, existentials, distincts, CC, GUI) o improvements (SMT-Lib2 front-end, intervals, case-splits, triggers, lets) o multiset ordering for AC(X) o manual lemma instantiation in the GUI
o bug fixes (distinct, let-in, explanations)
o -steps stops Alt-Ergo after a given number of steps o -max-split option to limit the number of case-splits o new polymorphic theory of arrays: ('a, 'b) farray o explanations (-proof option) o Built-in support for enumeration types o graphical frontend (altgr-ergo), needs to be compiled with make gui && make install-gui o new predicate distinct (a,b,c, ...) to express that constants a,b,c,... are pairwise distinct o new constructs: let x =
o New built-in syntax for the theory of arrays o Fixes a bug in the arithmetic module o Allows folding and unfolding of predicate definitions o Fixes other bugs
o experimental support for the theory of functional polymorphic arrays with the -arrays option o the -pairs option should now be used for the built-in support of polymorphic pairs o support the equality part of the omega test with the -omega option o partial support for non-linear arithmetics o support case split on integer variables o new support for Euclidean division and modulo operators o new environment variable ERGOLIB to specify the library directory
o support AC symbols o support for C-like hexadecimal floating-point constants o handle the division operator
o pretty output with the -color option o the SAT solver part is now equipped with a backjumping mechanism o now handles the flet and let SMT-lib constructs o goal directed strategy o pruning strategy (-select option) o incremental strategy for instantiation of lemmas o fail if a parameter is bound twice in a definition o treatment of existential formulas have been slightly improved o decision procedure for polymorphic pairs o decision procedure for bit-vectors o combination scheme for several decision procedures
o renamings in the interfaces o provides an API for alt-ergo (make api or make api.byte) o handles the modulo operator (%) as an uninterpreted symbol o allow labels on any term, not only on predicates
o trigger construction has been improved o preliminary implementation of combination scheme (Arithmetic+pairs) o the SAT loop has been improved
o new CC(X) architecture (it can know directly handle relation symbols) o fully handles the polymorphism of the logic
o first (beta) release