NEWS

New in spot 0.8.3a:

  * New features:
    - A new direct simulation reduction has been implemented.  It
      works directly on TGBA.  It's in src/tgbaalgos/simlation.hh,
      and it can be tested via ltl2tgba's -RDS option.
    - configure --without-included-lbtt will prevent LBTT from being
      configured and built.  This helps on systems (such as MinGW)
      where LBTT cannot be built.  The test-suite will skip any
      LBTT-based test if LBTT is missing.
  * Interface chances:
    - The old game-theory-based implementations for direct and delayed
      simulation reductions have been removed.  The old direct
      simulation would only work on degeneralized automata, and yet
      produce results inferior to the new direct simulation introduced
      in this release.  The implementation of delayed simulation was
      unreliable.  The function reduc_tgba_sim() has been kept
      for compatibility (it calls the new direct simulation whatever
      the type of simulation requested) and marked as deprecated.
      ltl2tgba's options -Rd, -RD are gone.  Options -R1t, -R1s,
      -R2s, and -R2t are deprecated and all made equivalent to -RDS.
    - The tgba_explicit hierarchy has been reorganized in order to
      make room for sba_explicit classes that share most of the code.
      The main consequence is that the tgba_explicit type no longuer
      exists.  However the tgba_explicit_number,
      tgba_explicit_formula, and tgba_explicit_string still do.

New in spot 0.8.3 (2012-03-09):

  * Support for both Python 2.x and Python 3.x.
    (Previous versions would only work with Python 2.x.)
  * The online ltl2tgba.html now stores its state in the URL so that
    history is preserved, and links to particular setups can be sent.
  * Bug fixes:
    - Fix a segfault in the compression code used by the -Z
      option of dve2check.
    - Fix a race condition in the CGI script.
    - Fix a segfault in the CGI script when computing a Büchi run.

New in spot 0.8.2 (2012-01-19):

  * configure now has a --disable-python option to disable
    the compilation of Python bindings.
  * Minor speedups in the Safra complementation.
  * Better memory management for the on-the-fly degeneralization
    algorithm.  This mostly benefits to the Safra complementation.
  * Bug fixes:
    - spot::ltl::length() forgot to count the '&' and '|' operators
      in an LTL formula.
    - minimize_wdba() could fail to mark some transiant SCCs as accepting,
      producing an automaton that was not fully minimized.
    - minimize_dfa() could produce incorrect automata, but it is not
      clear whether this could have had an inpact on WDBA minimization
      (the worse case is that some TGBA would not have been minimized
      when they could).
    - Fix a Python syntax error in the CGI script.
    - Fix compilation with g++ 4.0.
    - Fix a make check failure when valgrind is missing.

New in spot 0.8.1 (2011-12-18):

  * Only bug fixes:
    - When ltl2tgba is set to perform both WDBA minimization and
      degeneralization, do the latter only if the former failed.
      In previous version, automata were (uselessly) degeneralized
      before WDBA minimization, causing important slowdowns.
    - Fix compilation with Clang 3.0.
    - Fix a Makefile setup causing a "make check" failure on MacOS X.
    - Fix an mkdir error in the CGI script.

New in spot 0.8 (2011-11-28):

  * Major new features:
    - Spot can read DiVinE models.  See iface/dve2/README for details.
    - The genltl tool can now output 20 different LTL formula families.
      It also replaces the LTLcounter Perl scripts.
    - There is a printer and parser for Kripke structures in text format.
  * Major interface changes:
    - The destructor of all states is now private.  Any code that looks like
      "delete some_state;" will cause an compile error and should be
      updated to "some_state->destroy();".  This new syntax is supported
      since version 0.7.
    - The experimental Nips interface has been removed.
  * Minor changes:
    - The dotty_reachable() function has a new option "assume_sba" that
      can be used for rendering automata with state-based acceptance.
      In that case, acceptance states are displayed with a double
      circle. ltl2tgba (both command line and on-line) Use it to display
      degeneralized automata.
    - The dotty_reachable() function will also display transition
      annotations (as returned by the tgba::transitition_annotation()).
      This can be useful when displaying (small) state spaces.
    - Identifiers used to name atomic proposition can contain dots.
      E.g.: X.Y is now an atomic proposition, while it was understood
      as X&Y in previous versions.
    - The Doxygen documentation is no longer built as a PDF file.
  * Internal improvements:
    - The on-line ltl2tgba CGI script uses a cache to produce faster
      answers.
    - Better memory management for the states of explicit automata.
      Thanks to the aforementioned ->destroy() change, we can avoid
      cloning explicit states.
    - tgba_product has learned how to be faster when one of the operands
      is a Kripke structure (15% speedup).
    - The reduction rule for "a M b" has been improved: it can be
      reduced to "a & b" if "a" is a pure eventuallity.
    - More useless acceptance conditions are removed by SCC simplifications.
  * Bug fixes:
    - Safra complementation has been fixed in cases where more than
      one acceptance conditions where needed to convert the
      deterministic Streett automaton as a TGBA.
    - The degeneralization is now idempotent.  Previously, degeneralizing
      an already degeneralized automaton could add some states.
    - The degeneralization now has a deterministic behavior.  Previously
      it was possible to obtain different output depending on the
      memory layout.
    - Spot now outputs neverclaims with fully parenthesized guards.
      I.e., instead of
         (!x && y) -> goto S1
      it now outputs
         ((!(x)) && (y)) -> goto S1
      This prevents problems when the model defines `x' as
         #define x flag==0
      because !x then evaluated to (!flag)==0 instead of !(flag==0).

New in spot 0.7.1 (2001-02-07):

  * The LTL parser will accept operator ~ (for not) as well
    as --> and <--> (for implication and equivalence), allowing
    formulae from the Büchi Store to be read directly.
  * The neverclaim parser will accept guards of the form
        :: !(...) -> goto ...
    instead of the more commonly used
        :: (!(...)) -> goto ...
    This makes it possible to read neverclaims provided by the Büchi Store.
  * A new ltl2tgba option, -kt, will count the number of "sub-transitions".
    I.e., a transition labelled by "true" counts for 4 "sub-transitions"
    if the automaton uses 2 atomic propositions.
  * Bugs fixed:
    - Fix segfault during WDBA minimization on automata with useless states.
    - Use the included BuDDy library if the one already installed
      is older than the one distributed with Spot 0.7.
    - Fix two typos in the code of the CGI scripts.

New in spot 0.7 (2011-02-01):

  * Spot is now able to read an automaton expressed as a Spin neverclaim.
  * The "experimental" Kripke structure introduced in Spot 0.5 has
    been rewritten, and is no longer experimental.  We have a
    developement version of checkpn using it, and it should be
    released shortly after Spot 0.7.
  * The function to_spin_string(), that outputs an LTL formula using
    Spin's syntax, now takes an optional argument to request
    parentheses at all levels.
  * src/ltltest/genltl is a new tool that generates some interesting
    families of LTL formulae, for testing purpose.
  * bench/ltlclasses/ uses the above tool to conduct the same benchmark
    as in the DepCoS'09 paper by Cichoń et al.  The resulting benchmark
    completes in 12min, while it tooks days (or exhausted the memory)
    when the paper was written (they used Spot 0.4).
  * Degeneralization has again been improved in two ways:
    - It will merge degeneralized transitions that can be merged.
    - It uses a cache to speed up the improvement introduced in 0.6.
  * An implementation of Dax et al.'s paper for minimizing obligation
    formulae has been integrated.  Use ltl2tgba -Rm to enable this
    optimization from the command-line; it will have no effect if the
    property is not an obligation.
  * bench/wdba/ conducts a benchmark similar to the one on Dax's
    webpage, comparing the size of the automata expressing obligation
    formula before and after minimization.  See bench/wdba/README for
    results.
  * Using similar code, Spot can now construct deterministic monitors.
  * New ltl2tgba options:
    -XN: read an input automaton as a neverclaim.
    -C, -CR: Compute (and display) a counterexample after running the
             emptiness check.  With -CR, the counterexample will be
             replayed on the automaton to ensure it is correct
	     (previous version would always compute a replay a
	     counterexample when emptiness-check was enabled)
    -ks: traverse the automaton to compute its number of states and
         transitions (this is faster than -k which will also count
         SCCs and paths).
    -M: Build a deterministic monitor.
    -O: Tell whether a formula represents a safety, guarantee, or
        obligation property.
    -Rm: Minimize automata representing obligation properties.
  * The on-line tool to translate LTL formulae into automata
    has been rewritten and is now at http://spot.lip6.fr/ltl2tgba.html
    It requires a javascript-enabled browser.
  * Bug fixes:
    - Location of the errors messages in the TGBA parser where inaccurate.
    - Various warning fixes for different versions of GCC and Clang.
    - The neverclaim output with ltl2tgba -N or -NN used to ignore any
      automaton simplification performed after degeneralization.
    - The formula simplification based on universality and eventuality
      had a quadratic run-time.

New in spot 0.6 (2010-04-16):

  * Several optimizations to improve some auxiliary steps
    of the LTL translation (not the core of the translation):
    - Better degeneralization
    - SCC simplifications has been tuned for degeneralization
      (ltl2tgba now has two options -R3 and -R3f: the latter will
      remove every acceptance condition that used to be removed
      in Spot 0.5 while the former will leave useless acceptance conditions
      going to accepting SCC.  Experience shows that -R3 is more
      favorable to degeneralization).
    - ltl2tgba will perform SCC optimizations before degeneralization
      and not the converse
    - We added a syntactic simplification rule to rewrite F(a)|F(b) as F(a|b).
      We only had a rule for the more specific FG(a)|FG(b) = F(Ga|Gb).
    - The syntactic simplification rule for F(a&GF(b)) = F(a)&GF(b) has
      be disabled because the latter formula is in fact harder to translate
      efficiently.
  * New LTL operators: W (weak until) and its dual M (strong release)
    - Weak until allows many LTL specification to be specified more
      compactly.
    - All LTL translation algorithms have been updated to
      support these operators.
    - Although they do not add any expressive power, translating
      "a W b" is more efficient (read smaller output automaton) than
      translating the equivalent form using the U operator.
    - Basic syntactic rewriting rules will automatically rewrite "a U
      (b | G(a))" and "(a U b)|G(a)" as "a W b", so you will benefit
      from the new operators even if you do not use them.  Similar
      rewriting rules exist for R and M, although they are less used.
  * New options have been added to the CGI script for
    - SVG output
    - SCC simplifications
  * Bug fixes:
    - The precedence of the "->" and "<->" Boolean operators has been
      adjusted to better match other tools.
      Spot <= 0.5 used to parse "a & b -> c & d" as "a & (b -> c) & d";
      Spot >= 0.6 will parse it as "(a & b) -> (c & d)".
    - The random graph generator was fixed (again!) not to produce
      dead states as documented.
    - Locations in the error messages of the LTL parser were off by one.

New in spot 0.5 (2010-02-01):

  * We have setup two mailing lists:
    - <spot-announce@lrde.epita.fr> is read-only and will be used to
      announce new releases.  You may subscribe at
      https://www.lrde.epita.fr/mailman/listinfo/spot-announce
    - <spot@lrde.epita.fr> can be used to discuss anything related
      to Spot.  You may subscribe at
      https://www.lrde.epita.fr/mailman/listinfo/spot-announce
  * Two new LTL translations have been implemented:
    - eltl_to_tgba_lacim() is a symbolic translation for ELTL based on
      Couvreur's LaCIM'00 paper.  For this translation (available with
      ltl2tgba's option -le), all operators are described as finite
      automata.  A default set of operators is provided for LTL
      (option -lo) and user may add more automaton operators.
    - ltl_to_taa() is a translation based on Tauriainen's PhD thesis.
      LTL is translated to "self-loop" alternating automata
      and then to Transition-based Generalized Automata.  (ltl2tgba's
      option -taa).
    The "Couvreur/FM" translation remains the best LTL translation
    available in Spot.
  * The data structures used to represent LTL formulae have been
    overhauled, and it resulted in a big performence improvement
    (in time and memory consumption) for the LTL translation.
  * Two complementation algorithms for state-based Büchi automata
    have been implemented:
    - tgba_kv_complement is an on-the-fly implementation of the
      Kupferman-Vardi construction (TCS'05) for generalized acceptance
      conditions.
    - tgba_safra_complement is an implementation of Safra's
      complementation.  This algorithm takes a degeneralized Büchi
      automaton as input, but our implementation for the Streett->Büchi
      step will produce a generalized automaton in the end.
  * ltl2tgba has gained several options and the help text has been
    reorganized.  Please run src/tgbatest/ltl2tgba without arguments
    for details.  Couvreur/FM is now the default translation.
  * The ltl2tgba.py CGI script can now run standalone.  It also offers
    the Tauriainen/TAA translation, and some options for SCC-based
    reductions.
  * Automata using BDD-encoded transitions relation can now be pruned
    for useless states symbolically using the delete_unaccepting_scc()
    function.  This is ltl2tgba's -R3b option.
  * The SCC-based simplification (ltl2tgba's -R3 option) has been
    rewritten and improved.
  * The "*" symbol, previously parsed as a synonym for "&" is no
    longer recognized.  This makes room for an upcoming support of
    rational operators.
  * More benchmarks in the bench/ directory:
    - gspn-ssp/    some benchmarks published at ACSD'07,
    - ltlcounter/  translation of a class of LTL formulae used by
                     Rozier & Vardi at SPIN'07
    - scc-stats/   SCC statistics after translation of LTL formulae
    - split-product/ parallelizing gain after splitting LTL automata
  * An experimental Kripke interface has been developed to simplify
    the integration of third party tools that do not use acceptance
    conditions and that have label on states instead of transitions.
    This interface has not been used yet.
  * Experimental interface with the Nips virtual machine.
    It is not very useful as Spot isn't able to retrieve any property
    information from the model.  This will just check assertions.
  * Distribution:
    - The Boost C++ library is now required.
    - Update to Autoconf 2.65, Automake 1.11.1, Libtool 2.2.6b,
      Bison 2.4.1, and Swig 1.3.40.
    - Thanks to the newest Automake, "make check" will now
      run in parallel if you use "make -j2 check" or more.
  * Bug fixes:
    - Disable warnings from the garbage collection of BuDDy, it
      could break the standard output of ltl2tgba.
    - Fix several C++ constructs to ensure Spot will build with
      GCC 4.3, 4.4, and older 3.x releases, as well as with Intel's
      ICC compiler.
    - A very old bug in the hash function for LTL formulae caused Spot
      to sometimes (but very rarely) consider two different LTL formulae
      as equal.

New in spot 0.4 (2007-07-17):

  * Upgrade to Autoconf 2.61, Automake 1.10, Bison 2.3, and Swig 1.3.31.
  * Better LTL simplifications.
  * Don't initialize Buddy if it has already been initialized (in case
    the client software is already using Buddy).
  * Lots of work in the greatspn interface for our ACSD'05 paper.
  * Bug fixes:
    - Fix the random graph generator not to produce dead states as documented.
    - Fix synchronized product in case both side use acceptance conditions.
    - Fix some syntax errors with newer versions of GCC.

New in spot 0.3 (2006-01-25):

  * lbtt 1.2.0
  * The CGI script for LTL translation also offers emptiness check algorithms.
  * tau03_opt_search implements the "ordering heuristic".
    (Submitted by Heikki Tauriainen.)
  * A couple of bugs were fixed into the LTL or automata simplifications.

New in spot 0.2 (2005-04-08):

  * Emptiness checks:
    - the new spot::option_map class is used to pass options to
      emptiness-check algorithms.
    - the new emptiness_check_instantiator class is used to turn a
      string such as `algorithm(option1, option2)' into an actual
      instance of this emptiness-check algorithm with the given
      options.  All tools use this.
    - tau03_opt_search implements the "condition heuristic".
      (Suggested by Heikki Tauriainen.)
  * Minor bug fixes.

New in spot 0.1 (2005-01-31):

  * Emptiness checks:
    - They all follow the same interface, and gather statistical data.
    - New algorithms: gv04.hh, se05.hh, tau03.hh, tau03opt.hh
    - New options for couvreur99: poprem and group.
    - reduce_run() try to reduce accepting runs produced by emptiness checks.
    - replay_run() ensure accepting runs are actually accepting runs.
  * New testing tools:
    - ltltest/randltl: Generate random LTL formulae.
    - tgbatest/randtgba: Generate random TGBAs.  Optionally multiply them
        against random LTL formulae.  Optionally check them for emptiness
        with all available algorithms.  Optionally gather statistics.
  * bench/emptchk/: Contains scripts that benchmark emptiness-checks.
  * Split the degeneralization proxy in two:
    - tgba_tba_proxy  uses at most max(N,1) copies
    - tgba_sba_proxy  uses at most 1+max(N,1) copies and has a
                      state_is_accepting() method
  * tgba::transition_annotation annotate a transition with some string.
    This comes handy to associate that transition to its high-level name.
  * Preliminary support for Event-based GBA (the evtgba*/ directories).
    This might as well disappear in a future release.
  * LTL formulae are now sorting using their string representation, instead
    of their memory address (which is still unique).  This makes the output
    of the various functions more deterministic.
  * The Doxygen documentation is now organized using modules.

New in spot 0.0x (2004-08-13):

  * New atomic_prop_collect() function: collect atomic propositions
    in an LTL formula.
  * Fix several typos in documentation, and some warnings in the code.
  * Now compiles on Darwin and Cygwin.
  * Upgrade to Automake 1.9.1, and lbtt 1.1.2.
    (And drop support for older lbtt versions.)
  * Support newer versions of Valgrind (>= 2.1.0).

New in spot 0.0v (2004-06-29):

  * LTL formula simplifications using basic rewriting rules,
    a-la Wring syntactic approximations, and Etessami's universal
    and existential classes.
     - Function reduce() in ltlvisit/reduce.hh is the main interface.
     - Can be tested with the CGI script.
  * TGBA simplifications using direct simulation, delayed simulation,
    and SCC-based simplifications.  This is still experimental.
  * The LTL parser will now read LTL formulae written using Wring's syntax.
  * ltl2tgba_fm() now has options for on-the-fly fair-loop approximations,
    and Modella-like branching-postponement.
  * GreatSPN interface:
     - The `declarative_environment' is now part of Spot itself rather than
       part of the interface with GreatSPN.
     - the RG and SRG interface can deal with dead markings in three
       ways (omit deadlocks from the state graph, stutter on the deadlock
       and consider as a regular behavior, or stutter and distinguish the
       deadlock with a property).
     - update SSP interface to Soheib Baarir latest work.
  * Preliminary Python bindings for BuDDy's FDD and BVEC.
  * Upgrade to BuDDy 2.3.

New in spot 0.0t (2004-04-23):

  * `emptiness_check':
      - fix two bugs in the computation of the counter example,
      - revamp the interface for better customization.
  * `never_claim_reachable': new function.
  * Introduce annonymous BDD variables in `bdd_dict', and start
    to use it in `ltl_to_tgba_fm'.
  * Offer never claim in the CGI script.
  * Rename EESRG as SSP, and offer specialized variants of the
    emptiness_check.

New in spot 0.0r (2004-03-08):

  * In ltl_to_tgba_fm:
    - New option `exprop' to optimize determinism.
    - Make the `symbolic indentification' from 0.0p optional.
  * `nonacceptant_lbtt_reachable' new function to help getting
    accurate statistics from LBTT.
  * Revamp the cgi script's user interface.
  * Upgrade to lbtt 1.0.3, swig 1.3.21, automake 1.8.3

New in spot 0.0p (2004-02-03):

  * In ltl_to_tgba_fm:
    - identify states with identical symbolic expansions
      (i.e., identical continuations)
    - use Acc[b] as acceptance condition for Fb, not Acc[Fb].
  * Update and speed-up the cgi script.
  * Improve degeneralization.

New in spot 0.0n (2004-01-13):

  * emptiness_check::check2() is a variant of Couvreur's emptiness check that
    explores visited states first.
  * Build the EESRG supporting code condinally, as the associated
    GreatSPN changes have not yet been contributed to GreatSPN.
  * Add a powerset algorithm (determinize TGBA ignoring acceptance
    conditions, i.e., as if they were used to recognize finite languages).
  * tgba_explicit::merge_transitions: merge transitions with same source,
    destination, and acceptance condition.
  * Run test cases within valgrind.
  * Various bug fixes.

New in spot 0.0l (2003-12-01):

  * Computation of prime implicants.  This simplify the output of
    ltl_to_tgba_fm, and allows conditions to be output as some of
    product in dot output.
  * Optimize translation of GFy in ltl_to_tgba_fm.
  * tgba_explicit supports arbitrary binary formulae on transitions
    (only conjunctions were allowed).

New in spot 0.0j (2003-11-03):

  * Use hash_map's instead of map's almost everywhere.
  * New emptiness check, based on Couvreur's algorithm.
  * LTL propositions can be put inside doublequotes to disambiguate
    some constructions.
  * Preliminary support for GreatSPN's EESRG.
  * Various bug fixes.

New in spot 0.0h (2003-08-18):

  * More python bindings:
    - "import buddy" works (see wrap/python/tests/bddnqueen.py for an example),
    - almost all the Spot API is now available via "import spot".
  * wrap/python/cgi/ltl2tgba.py is an LTL-to-Büchi translator that
    work as as a cgi script.
  * Couvreur's FM'99 ltl-to-tgba translation.

New in spot 0.0f (2003-08-01):

  * More python bindings, still only for the spot::ltl:: namespace.
  * Functional GSPN interface.  (Enable with --with-gspn=directory.)
  * The LTL scanner recognizes /\, \/, and xor.
  * Upgrade to lbtt 1.0.2.
  * tgba_tba_proxy is an on-the-fly degeneralizer.
  * Implements the "magic search" algorithm.
    (Works only on a tgba_tba_proxy.)
  * Tgba's output algorithms (save(), dotty()) now non-recursive.
  * During products, succ_iter will optimize its set of successors
    using information computed from the current product state.
  * BDD dictionnaries are now shared between automata and.  This
    gets rid of all the BDD-variable translating machinery.

New in spot 0.0d (2003-07-13):

  * Optimize translation of G operators occurring at the root
    of a formula (or its immediate children when the root is a
    conjunction).  This saves two BDD variables per G operator.
  * Distribute lbtt, and run it during `make check'.
  * First sketch of GSPN interface.
  * succ_iter_concreate::next() completely rewritten.
  * Transitions are now labelled by boolean formulae (not only
    conjunctions).
  * Documentation:
    - Output collaboration diagrams.
    - Build and distribute PDF manual.
  * Many bug fixes.

New in spot 0.0b (2003-06-26):

  * Everything.