Annonce October 2013

annonce@lrde.epita.fr

3 participants
3 discussions

[Seminaire-LRDE] Mercredi 13 novembre 2013: Dodji Seketeli, Red Hat

by Daniela Becker

Chers collègues, La prochaine session du séminaire Performance et Généricité du LRDE (Laboratoire de Recherche et Développement de l'EPITA) aura lieu le Mercredi 13 novembre 2013 (11h--12h30), Salle Lα du LRDE. Au programme: * 11h-12h30: Address & Thread Sanitizer in GCC: Etat Actuel et Orientation Future -- Dodji Seketeli, Red Hat http://gcc.gnu.org Address & Thread sanitizer sont des outils destinés à détecter les erreurs d'accès à la mémoire ainsi que les erreurs d'accès concurrents en environnement multi-threads. Ces outils sont constitués de deux parties logiques distinctes: une partie instrumentant le code généré de manière statique, et un environnement d'exécution. Cet exposé présente l'implémentation de Address & Thread Sanitizer dans GCC, les principes de fonctionnement de l'environnement d'exécution de ces deux outils ainsi que les futures directions du projet. -- Dodji Seketeli est ingénieur dans l'équipe Tools de Red Hat. Il travaille sur la suite des compilateurs GNU, principalement sur les compilateurs C et C++. Pendant son temps libre, lorsqu'il ne joue pas avec son épouse et ses enfants, il maintient Nemiver, le debuggeur graphique du projet d'environnement de bureau libre GNOME. En dehors des logiciels libres, il s'intéresse aux arts martiaux et à l'histoire. Pour plus de renseignements, consultez http://seminaire.lrde.epita.fr/. L'entrée du séminaire est libre. Merci de bien vouloir diffuser cette information le plus largement possible. -- Akim Demaille Akim.Demaille(a)lrde.epita.fr _______________________________________________ Seminaire mailing list Seminaire(a)lrde.epita.fr https://lists.lrde.epita.fr/listinfo/seminaire

11 years, 1 month

Re: [Lrde Annonce] New publication: LPAR'13

by Etienne Renault

We are pleased to inform you that the following paper has been accepted in the 19th International Conference on Logic for Programming, Artificial Intelligence, and Reasoning (LPAR). Please find the title and abstract below. Title and corresponding authors: "Three SCC-based Emptiness Checks for Generalized Büchi Automata" E. Renault(1), A. Duret-Lutz(1), F. Kordon(2), and D. Poitrenaud(2) (1) LRDE-EPITA, www.lrde.epita.fr (2) UPMC-LIP6, www.lip6.fr Abstract: The automata-theoretic approach for the verification of linear time properties involves checking the emptiness of a Büchi automaton. However generalized Büchi automata, with multiple acceptance sets, are preferred when verifying under weak fairness hypotheses. Existing emptiness checks for which the complexity is independent of the number of acceptance sets are all based on the enumeration of Strongly Connected Components (SCCs). In this paper, we review the state of the art SCC enumeration algorithms to study how they can be turned into emptiness checks. This leads us to define two new emptiness check algorithms (one of them based on the Union Find data structure), introduce new optimizations, and show that one of these can be of benefit to a classic SCCs enumeration algorithm. We have implemented all these variants to compare their relative performances and the overhead induced by the emptiness check compared to the corresponding SCCs enumeration algorithm. Our experiments shows that these three algorithms are comparable.

11 years, 2 months

Spot 1.2 has been released

by Alexandre Duret-Lutz

I'm very pleased to announce the release of Spot 1.2. Spot is a model-checking library developed collaboratively by LRDE and LIP6. It provides algorithms and data structures to implement the automata-theoretic approach to LTL model checking. This release contains several new features (summarized below), but the most notable are the interface with ltl2dstar (i.e., Spot can read deterministic Rabin and Streett automata and convert them into Büchi automata) and algorithms for minimizing deterministic TGBA or BA using a SAT-solver. You can find the new release here: http://spot.lip6.fr/dl/spot-1.2.tar.gz Please report any issue to <spot(a)lrde.epita.fr>. New in spot 1.2 (2013-10-01) * Changes to command-line tools: - ltlcross has a new option --color to color its output. It is enabled by default when the output is a terminal. - ltlcross will give an example of infinite word accepted by the two automata when the product between a positive automaton and a negative automaton is non-empty. - ltlcross can now read the Rabin and Streett automata output by ltl2dstar. This type of output should be specified using '%D': ltlcross 'ltl2dstar --ltl2nba=spin:path/to/ltl2tgba@-s %L %D' However because Spot only supports Büchi acceptance, these Rabin and Streett automata are immediately converted to TGBAs before further processing by ltlcross. This is still interesting to search for bugs in translators to Rabin or Streett automata, but the statistics (of the resulting TGBAs) might not be very relevant. - When ltlcross obtains a deterministic automaton from a translator it will now complement this automaton to perform additional intersection checks. This is complementation is done only for deterministic automata (because that is cheap) and can be disabled with --no-complement. - To help with debugging problems detected by ltlcross, the environment variables SPOT_TMPDIR and SPOT_TMPKEEP control where temporary files are created and if they should be erased. Read the man page of ltlcross for details. - There is a new command, named dstar2tgba, that converts a deterministic Rabin or Streett automaton (expressed in the output format of ltl2dstar) into a TGBA, BA or Monitor. In the case of Rabin acceptance, the conversion will output a deterministic Büchi automaton if one such automaton exist. Even if no such automaton exists, the conversion will actually preserves the determinism of any SCC that can be kept deterministic. In the case of Streett acceptance, the conversion produces non-deterministic Büchi automata with Generalized acceptance. These are then degeneralized if requested. See http://spot.lip6.fr/userdoc/dstar2tgba.html for some examples, and the man page for more reference. - The %S escape sequence used by ltl2tgba --stats to display the number of SCCs in the output automaton has been renamed to %c. This makes it more homogeneous with the --stats option of the new dstar2tgba command. Additionally, the %p escape can now be used to show whether the output automaton is complete, and the %r escape will give the number of seconds spent building the output automaton (excluding the time spent parsing the input). - ltl2tgba, ltl2tgta, and dstar2tgba have a --complete option to output complete automata. - ltl2tgba, ltl2tgta, and dstar2tgba can use a SAT-solver to minimize deterministic automata. Doing so is only needed on properties that are stronger than obligations (for obligations our WDBA-minimization procedure will return a minimimal deterministic automaton more efficiently) and is disabled by default. See the spot-x(7) man page for documentation about the related options: sat-minimize, sat-states, sat-acc, state-based. See also http://spot.lip6.fr/userdoc/satmin.html for some examples. - ltlfilt, genltl, and randltl now have a --latex option to output formulas in a way that its easier to embed in a LaTeX document. Each operator is output as a command such as \U, \F, etc. doc/tl/spotltl.sty gives one possible definition for each macro. - ltlfilt, genltl, and randltl have a new --format option to indicate how to present the output formula, possibly with information about the input. - ltlfilt as a new option, --relabel-bool, to abstract independent Boolean subformulae as if they were atomic propositions. For instance "a & GF(c | d) & b & X(c | d)" would be rewritten as "p0 & GF(p1) & Xp1". * New functions and classes in the library: - dtba_sat_synthetize(): Use a SAT-solver to build an equivalent deterministic TBA with a fixed number of states. - dtba_sat_minimize(), dtba_sat_minimize_dichotomy(): Iterate dtba_sat_synthetize() to reduce the number of states of a TBA. - dtgba_sat_synthetize(), dtgba_sat_minimize(), dtgba_sat_minimize_dichotomy(): Likewise, for deterministic TGBA. - is_complete(): Check whether a TGBA is complete. - tgba_complete(): Complete an automaton by adding a sink state if needed. - dtgba_complement(): Complement a deterministic TGBA. - satsolver(): Run an (external) SAT solver, honoring the SPOT_SATSOLVER environment variable if set. - tba_determinize(): Run a power-set construction, and attempt to fix the acceptance simulation to build a deterministic TBA. - dstar_parse(): Read a Streett or Rabin automaton in ltl2dstar's format. Note that this format allows only deterministic automata. - nra_to_nba(): Convert a (possibly non-deterministic) Rabin automaton to a non-deterministic Büchi automaton. - dra_to_ba(): Convert a deterministic Rabin automaton to a Büchi automaton, preserving acceptance in all SCCs where this is possible. - nsa_to_tgba(): Convert a (possibly non-deterministic) Streett automaton to a non-deterministic TGBA. - dstar_to_tgba(): Convert any automaton returned by dstar_parse() into a TGBA. - build_tgba_mask_keep(): Build a masked TGBA that shows only a subset of states of another TGBA. - build_tgba_mask_ignore(): Build a masked TGBA that ignore a subset of states of another TGBA. - class tgba_proxy: Helps writing on-the-fly algorithms that delegate most of their methods to the original automaton. - class bitvect: A dynamic bit vector implementation. - class word: An infinite word, stored as prefix + cycle, with a simplify() methods to simplify cycle and prefix in obvious ways. - class temporary_file: A temporary file. Can be instanciated with create_tmp_file() or create_open_tmpfile(). - count_state(): Return the number of states of a TGBA. Implement a couple of specializations for classes where is can be know without exploration. - to_latex_string(): Output a formula using LaTeX syntax. - relabel_bse(): Relabeling of Boolean Sub-Expressions. Implements ltlfilt's --relabel-bool option describe above. * Noteworthy internal changes: - When minimize_obligation() is not given the formula associated to the input automaton, but that automaton is deterministic, it can still attempt to call minimize_wdba() and check the correcteness using dtgba_complement(). This allows dstar2tgba to apply WDBA-minimization on deterministic Rabin automata. - tgba_reachable_iterator_depth_first has been redesigned to effectively perform a DFS. As a consequence, it does not inherit from tgba_reachable_iterator anymore. - postproc::set_pref() was used to accept an argument among Any, Small or Deterministic. These can now be combined with Complete as Any|Complete, Small|Complete, or Deterministic|Complete. - operands of n-ary operators (like & and |) are now ordered so that Boolean terms come first. This speeds up syntactic implication checks slightly. Also, literals are now sorted using strverscmp(), so that p5 comes before p12. - Syntactic implication checks have been generalized slightly (for instance 'a & b & F(a & b)' is now reduced to 'a & b' while it was not changed in previous versions). - All the parsers implemented in Spot now use the same type to store locations. - Cleanup of exported symbols All symbols in the library now have hidden visibility on ELF systems. Public classes and functions have been marked explicitely for export with the SPOT_API macro. During this massive update, some of functions that should not have been made public in the first place have been moved away so that they can only be used from the library. Some old of unused functions have been removed. removed: - class loopless_modular_mixed_radix_gray_code hidden: - class acc_compl - class acceptance_convertor - class bdd_allocator - class free_list * Bug fixes: - Degeneralization was not indempotant on automata with an accepting initial state that was on a cycle, but without self-loop. - Configuring with --enable-optimization would reset the value of CXXFLAGS. -- Alexandre Duret-Lutz

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Annonce October 2013