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 version 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
Spot 1.1.4 has been released.
This maintenance release fixes a couple of bugs reported over the
last weeks. These include a regression preventing 1.1.3 to parse
neverclaims produced by ltl2ba or ltl3ba, and a bug in the
interpretation of the closure of some SERE.
You can download the new release here:
http://spot.lip6.fr/dl/spot-1.1.4.tar.gz
New in spot 1.1.4 (2013-07-29)
* Bug fixes:
- The parser for neverclaim, updated in 1.1.3, would fail to
parse guards of the form (a) || (b) output by ltl2ba or
ltl3ba, and would only understand ((a) || (b)).
- When used from ltlcross, the same parser would fail to
parse further neverclaims after the first failure.
- Add a missing newline in some error message of ltlcross.
- Expressions like {SERE} were wrongly translated and simplified
for SEREs that accept the empty word: they were wrongly reduced
to true. Simplification and translation rules have been fixed,
and the doc/tl/tl.pdf specifications have been updated to better
explain that {SERE} has the semantics of a closure operator that
is not exactly what one could expect after reading the PSL
standard.
- Various typos.
--
Alexandre Duret-Lutz (off for three weeks)
I'm pleased to announce the release of Spot 1.1.3.
This maintenance release fixes a couple of bugs reported over the
last month, and add support for reading the new neverclaims output by
Spin 6.24+ (they can be parsed by ltlcross, for instance).
You can download the new release here:
http://spot.lip6.fr/dl/spot-1.1.3.tar.gz
New in spot 1.1.3 (2013-07-09)
* New feature:
- The neverclaim parser now understands the new style of output
used by Spin 6.24 and later.
* Bug fixes:
- The scc_filter() function could abort with a BDD error. If all
the acceptance sets of an SCC but the first one were useless.
- The script in bench/spin13/ would not work on MacOS X because
of some non-portable command.
- A memory corruption in ltlcross.
--
Alexandre Duret-Lutz
Spot 1.1.2 has been released.
This maintainance release fixes a couple minor bugs. If you have
version 1.1.1 already installed, there is no reason to upgrade unless
you are using ltlcross to generate statistics.
You can download the new release here:
http://spot.lip6.fr/dl/spot-1.1.2.tar.gz
New in spot 1.1.2 (2013-06-09)
* Bug fixes:
- Uninitialized variables in ltlcross (affect the count of terminal
weak, and strong SCCs).
- Workaround an old GCC bug to allow compilation with g++ <= 4.5
- Fix several Doxygen comments so that they display correctly.
--
Alexandre Duret-Lutz
This is to announce the release of Spot 1.1.1.
The main motivation for this release is to fix a bug introduced in
version 1.1 in the post-processing of (degeneralized) Büchi automata.
Although the NEWS excerpt at the end of this email shows several
new features, most of them are related to the discovery and fix of
this bug:
1) With this release, ltl2tgba --ba --lbtt has been changed to
output automata using the state-based acceptance flavor of
the LBTT format. This makes more sense when you work with
Büchi automata.
2) This lead to the discovery that previously, when --lbtt always
output automata with transition-based acceptance, there were
some rare formulas where ltl2tgba --ba --lbtt could output
automata that where not Büchi automata (although they had
the correct language), and worse: ltl2tgba --spin could
output an incorrect neverclaim.
3) fixing this required to reimplement two functions we started using
in 1.0 but that messed the structure of Büchi automata: namely
reverse simulation and SCC-based simplification of acceptance
condition.
Two small and easy options have also been added to ltlcross.
You can find the new release here:
http://spot.lip6.fr/dl/spot-1.1.1.tar.gz
A summary of the changes follows. Please report any issue
to <spot(a)lrde.epita.fr>.
New in spot 1.1.1 (2013-05-13):
* New features:
- lbtt_reachable(), the function that outputs a TGBA in LBTT's
format, has a new option to indicate that the TGBA being printed
is in fact a Büchi automaton. In this case it outputs an LBTT
automaton with state-based acceptance.
The output of the guards has also been changed in two ways:
1. atomic propositions that do not match p[0-9]+ are always
double-quoted. This avoids issues where t or f were used as
atomic propositions in the formula, output as-is in the
automaton, and read back as true or false. Other names that
correspond to LBT operators would cause problem as well.
2. formulas that label transitions are now output as
irredundant-sums-of-products.
- 'ltl2tgba --ba --lbtt' will now output automata with state-based
acceptance. You can use 'ltl2tgba --ba --lbtt=t' to force the
output of transition-based acceptance like in the previous
versions.
Some illustrations of this point and the previous one can be
found in the man page for ltl2tgba(1).
- There is a new function scc_filter_states() that removes all
useless states from a TGBA. It is actually an abbridged version
of scc_filter() that does not alter the acceptance conditions of
the automaton. scc_filter_state() should be used when
post-processing TGBAs that actually represent BAs.
- simulation_sba(), cosimulation_sba(), and
iterated_simulations_sba() are new functions that apply to TGBAs
that actually represent BAs. They preserve the imporant
property that if a state of the BA is is accepting, the outgoing
transitions of that state are all accepting in the TGBA that
represent the BA. This is something that was not preserved by
functions cosimultion() and iterated_simulations() as mentionned
in the bug fixes below.
- ltlcross has a new option --seed, that makes it possible to
change the seed used by the random graph generator.
- ltlcross has a new option --products=N to check the result of
each translation against N different state spaces, and everage
the statistics of these N products. N default to 1; larger
values increase the chances to detect inconsistencies in the
translations, and also make the average size of the product
built against the translated automata a more pertinent
statistic.
- bdd_dict::unregister_all_typed_variables() is a new function,
making it easy to unregister all BDD variables of a given type
owned by some object.
* Bug fixes:
- genltl --gh-r generated the wrong formulas due to a typo.
- ltlfilt --eventual and --universal were not handled properly.
- ltlfilt --stutter-invariant would trigger an assert on PSL formulas.
- ltl2tgba, ltl2tgta, ltlcross, and ltlfilt, would all choke on empty
lines in a file of formulas. They now ignore empty lines.
- The iterated simulation applied on degeneralized TGBA was bogus
for two reasons: one was that cosimulation was applied using the
generic cosimulation for TGBA, and the second is that
SCC-filtering, performed between iterations, was also a
TGBA-based algorithm. Both of these algorithms could lose the
property that if a TGBA represents a BA, all the outgoing
transitions of a state should be accepting. As a consequence, some
formulas where translated to incorrect Büchi automata.
--
Alexandre Duret-Lutz
We are pleased to announce the release of Spot 1.1.
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 features several improvements developped with our
collegues from the Mazaryk University (also authors of the ltl3ba
translator) as detailed in the following paper:
Tomáš Babiak, Thomas Badie, Alexandre Duret-Lutz, Mojmír
Křetínský, Jan Strejček: Compositional Approach to Suspension and
Other Improvements to LTL Translation. To appear in the
proceedings of SPIN'13.
You can find the new release here:
http://spot.lip6.fr/dl/spot-1.1.tar.gz
A summary of the changes follows. Please report any issue
to <spot(a)lrde.epita.fr>.
New in spot 1.1 (2013-04-28):
* New features in the library:
- The postprocessor class now takes an optional option_map
argument that can be used to specify fine-tuning options, making
it easier to benchmark different scenarios while developing new
postprocessings.
- A new translator class implements a complete translation chain,
from LTL/PSL to TGBA/BA/Monitor. It performs pre- and
post-processings in addition to the core translation, and offers
an interface similar to that used in the postprocessor class, to
specify the intent of the translation.
- The degeneralization algorithm has learned three new tricks:
level reset, level caching, and SCC-based ordering. The former
two are enabled by default. Benchmarking has shown that the
latter one does not always have a positive effect, so it is
disabled by default. (See SPIN'13 paper.)
- The scc_filter() function, which removes dead SCCs and also
simplify acceptance conditions, has learnt how to simplify
acceptance conditions in a few tricky situations that were not
simplified previously. (See SPIN'13 paper.)
- An experimental "don't care" (direct) simulation has been
implemented. This simulations consider the acceptance
of out-of-SCC transitions as "don't care". It is not
enabled by default because it currently is very slow.
- remove_x() is a function that take a formula, and rewrite it
without the X operator. The rewriting is only correct for
stutter-insensitive LTL formulas (See K. Etessami's paper in IFP
vol. 75(6). 2000) This algorithm is accessible from the
command-line using ltlfilt's --remove-x option.
- is_stutter_insensitive() takes any LTL formula, and check
whether it is stutter-insensitive. This algorithm is accessible
from the command-line using ltlfilt's --stutter-insensitive
option.
- A new translation, called compsusp(), for "Compositional
Suspension" is implemented on top of ltl_to_tgba_fm().
(See SPIN'13 paper.)
- Some experimental LTL rewriting rules that trie to gather
suspendable formulas are implemented and can be activated
with the favor_event_univ option of ltl_simplifier. As
always please check doc/tl/tl.tex for the list of rules.
- Several functions have been introduced to check the
strength of an SCC.
is_inherently_weak_scc()
is_weak_scc()
is_syntactic_weak_scc()
is_complete_scc()
is_terminal_scc()
is_syntactic_terminal_scc()
Beware that the costly is_weak_scc() function introduced in Spot
1.0, which is based on a cycle enumeration, has been renammed to
is_inherently_weak_scc() to match established vocabulary.
* Command-line tools:
- ltl2tgba and ltl2tgta now honor a new --extra-options (or -x)
flag to fine-tune the algorithms used. The available options
are documented in the spot-x (7) manpage. For instance use '-x
comp-susp' to use the afore-mentioned compositional suspension.
- The output format of 'ltlcross --json' has been changed slightly.
In a future version we will offer some reporting script that turn
such JSON output into various tables and graphs, and these change
are required to make the format usable for other benchmarks (not
just ltlcross).
- ltlcross will now count the number of non-accepting, terminal,
weak, and strong SCCs, as well as the number of terminal, weak,
and strong automata produced by each tool.
* Documentation:
- org-mode files used to generate the documentation about
command-line tools (shown at http://spot.lip6.fr/userdoc/tools.html)
is distributed in doc/org/. The resulting html files are also
in doc/userdoc/.
* Bug fixes:
- There was a memory leak in the LTL simplification code, that could
only be triggered when disabling advanced simplifications.
- The translation of the PSL formula !{xxx} was incorrect when xxx
simplified to false.
- Various warnings triggered by new compilers.
--
Alexandre Duret-Lutz
e are pleased to announce the release of Spot 1.0.2.
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 second maintainance release fixes couple of bugs, the most
serious being in web interface, and adds two minor new features.
You can find the new release here:
http://spot.lip6.fr/dl/spot-1.0.2.tar.gz
A summary of the changes follows. Please report any issue
to <spot(a)lrde.epita.fr>.
New in spot 1.0.2 (2013-03-06):
* New features:
- the on-line ltl2tgba.html interface can output deterministic or
non-deterministic monitors. However, and unlike the ltl2tgba
command-line tool, it doesn't different output formats.
- the class ltl::ltl_simplifier now has an option to rewrite Boolean
subformulaes as irredundante-sum-of-product during the simplification
of any LTL/PSL formula. The service is also available as a method
ltl_simplifier::boolean_to_isop() that applies this rewriting
to a Boolean formula and implements a cache.
ltlfilt as a new option --boolean-to-isop to try to apply the
above rewriting from the command-line:
% ltlfilt --boolean-to-isop -f 'GF((a->b)&(b->c))'
GF((!a & !b) | (b & c))
This is currently not used anywhere else in the library.
* Bug fixes:
- 'ltl2tgba --high' is documented to be the same as 'ltl2tgba',
but by default ltl2tgba forgot to enable LTL simplifications based
on language containment, which --high do enable. There are now
enabled by default.
- the on-line ltl2tgba.html interface failed to output monitors,
testing automata, and generalized testing automata due to two
issues with the Python bindings. It also used to display
Testing Automaton Options when the desired output was set to Monitor.
- bench/ltl2tgba would not work in a VPATH build.
- a typo caused some .dir-locals.el configuration parameters to be
silently ignored by emacs
- improved Doxygen comments for formula_to_bdd, bdd_to_formula,
and bdd_dict.
- src/tgbatest/ltl2tgba (not to be confused with src/bin/ltl2tgba)
would have a memory leak when passed the conflicting option -M
and -O. It probably has many other problems. Do not use
src/tgbatest/ltl2tgba if you are not writing a test case for
Spot. Use src/bin/ltl2tgba instead.
--
Alexandre Duret-Lutz
We are pleased to announce the release of Spot 1.0.1.
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 maintainance release mainly addresses a couple of minor bugs
uncovered in the last three months, and prunes some old code. The
main change is probably that LBTT has been removed from the
distribution, as promised in the previous release notes.
You can find the new release here:
http://spot.lip6.fr/dl/spot-1.0.1.tar.gz
A summary of the changes follows. Please report any issue
to <spot(a)lrde.epita.fr>.
New in spot 1.0.1 (2013-01-23):
* Bug fixes:
- Two executions of the simulation reductions could produce
two isomorphic automata, but with transitions in a different
order.
- ltlcross did not diagnose write errors to temporary files,
and certain versions of g++ would warn about it.
- "P0.init" is parsed as an atomic even without the double quotes,
but it was always output with double quotes. This version will
not quote this atomic proposition anymore.
- "U", "W", "M", "R" were correctly parsed as atomic propositions
(instead of binary operators) when placed in double quotes, but
on output they were output without quotes, making the result
unparsable.
- the to_lbt_string() functions would always output a trailing space.
This is not the case anymore.
- tgba_product::transition_annotation() would segfault when
called in a product against a Kripke structure.
* Minor improvements:
- Four new LTL simplifications rules:
GF(a|Xb) = GF(a|b)
GF(a|Fb) = GF(a|b)
FG(a&Xb) = FG(a&b)
FG(a&Gb) = FG(a&b)
- The on-line version of ltl2tgba now displays edge and
transition counts, just as the ltlcross tool.
- ltlcross will display the number of timeouts at the end
of its execution.
- ltlcross will diagnose tools with missing input or
output %-sequence before attempting to run any of them.
- The parser for LBT's prefix-style LTL formulas will now
read atomic propositions that are not of the form p1, p2...
This makes it possible to process formulas written in
ltl2dstar's syntax.
* Pruning:
- lbtt has been removed from the distribution. A copy of the last
version we distributed is still available at
http://spot.lip6.fr/dl/lbtt-1.2.1a.tar.gz
and our test suite will use it if it is installed, but the same
tests are already performed by ltlcross.
- the bench/ltl2tgba/ benchmark, that used lbtt to compare various
LTL-to-Büchi translators, has been updated to use ltlcross. It
now output summary tables in LaTeX. Support for Modella (no
longer available online), and Wring (requires a too old Perl
version) have been dropped.
- the half-baked and underdocumented "Event TGBA" support in
src/evtgba*/ has been removed, as it was last worked on in 2004.
After 9 years of releases with a leading "0." in their version number,
this might be unexpected:
We are pleased to announce the release of Spot 1.0.
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 major new releases features a set of completely rewritten
command-line tools, an implementation of reverse simulation,
and support for testing automata.
You can find the new release here:
http://spot.lip6.fr/dl/spot-1.0.tar.gz
A more detailed listing of the changes follows.
New in spot 1.0 (2012-10-27):
* License change: Spot is now distributed using GPL v3+ instead
of GPL v2+. This is because we started using some third-party
files distributed under GPL v3+.
* Command-line tools
Useful command-line tools are now installed in addition to the
library. Some of these tools were originally written for our test
suite and had evolved organically into useful programs with crappy
interfaces: they have now been rewritten with better argument
parsing, saner defaults, and they come with man pages.
- genltl: Generate LTL formulas from scalable patterns.
This offers 20 patterns so far.
- randltl: Generate random LTL/PSL formulas.
- ltlfilt: Filter lists of formulas according to several criteria
(e.g., match only safety formulas that are larger than
some given size). Besides being used as a "grep" tool
for formulas, this can also be used to convert
files of formulas between different syntaxes, apply
some simplifications, check whether to formulas are
equivalent, ...
- ltl2tgba: Translate LTL/PSL formulas into Büchi automata (TGBA,
BA, or Monitor). A fundamental change to the
interface is that you may now specify the goal of the
translation: do you you favor deterministic or smaller
automata?
- ltl2tgta: Translate LTL/PSL formulas into Testing Automata.
- ltlcross: Compare the output of translators from LTL/PSL to
Büchi automata, to find bug or for benchmarking. This
is essentially a Spot-based reimplementation of LBTT
that supports PSL in addition to LTL, and that can
output more statistics.
An introduction to these tools can be found on-line at
http://spot.lip6.fr/userdoc/tools.html
The former test versions of genltl and randltl have been removed
from the source tree. The old version of ltl2tgba with its
gazillion options is still is src/tgbatest/ and is meant to be
used for testing only. Although ltlcross is meant to replace
LBTT, we are still using both tools in this release; however this
is likely to be the last release of Spot that redistributes LBTT.
* New features in the Spot library:
- Support for various flavors of Testing Automata.
The flavors are:
+ "classical" Testing Automata, as used for instance by
Geldenhuys and Hansen (Spin'06), using Büchi and
livelock acceptance conditions.
+ Generalized Testing Automata, extending the previous
with multiple Büchi acceptance sets.
+ Transition-based Generalized Testing Automata moving Büchi
acceptance to transitions, and getting rid of livelock
acceptance conditions by expliciting stuttering self-loops.
Supporting algorithms include anything required to run
the automata-theoretic approach using testing automata:
+ dedicated synchronized product
+ dedicated emptiness-check for TA and GTA, as these
may require two passes because of the two kinds of
acceptance, while a TGTA can be checked for emptiness
with the same one-pass algorithm as a TGBA.
+ conversion from a TGBA to any of the above kind, with
options to reduce these automata with bisimulation,
and to produce a BA/GBA that require a single pass
(at the expense of determinism).
+ output in dot format for display
A discussion of these automata, part of Ala Eddine BEN SALEM's
PhD work, should appear in ToPNoC VI (LNCS 7400). The web-based
interface and the aforementioned ltl2tgta tool can be used
to build testing automata.
- TGBA can now be reduced by Reverse Simulation (in addition to
the Direct Simulation introduced in 0.9). A function called
iterated_simulations() will alternate direct and reverse
simulations in a loop as long as it diminishes the size of the
automaton.
- The enumerate_cycles class implements the Loizou-Thanisch
algorithm to enumerate elementary cycles in a SCC. As an
example of use, is_weak_scc() will tell whether an SCC is
inherently weak (all its cycles are accepting, or none of them
are).
- parse_lbt() will parse an LTL formula expressed in the prefix
syntax used (at least) by LBT, LBTT and Scheck.
to_lbt_string() can be used to print an LTL formula using this
syntax.
- to_wring_string() can be used to print an LTL formula into
Wring's syntax.
- The LTL/PSL parser now has a lenient mode that can be useful
to interpret atomic proposition with language-specific constructs.
In lenient mode, any (...) or {...} block that cannot be parsed
as formula will be assumed to be an atomic proposition.
For instance the input (a < b) U (process[2]@ok), normally
flagged as a syntax error, is read as "a < b" U "process[2]@ok"
in lenient mode.
- minimize_obligation() has a new option to disable WDBA
minimization it cases it would produce a deterministic automaton
that is bigger than the original TGBA. This can help
choosing between less states or more determinism.
- new functions is_deterministic() and count_nondet_states()
(The count of nondeterministic states is now displayed on
automata generated with the web interface.)
- A new class, "postprocessor", makes it easier to apply
all available simplification algorithms on a TGBA/BA/Monitors.
* Minor changes:
- The '*' operator can (again) be used as an AND in LTL formulas.
This is for compatibility with formula written in Wring's
syntax. However inside SERE it is interpreted as the Kleen
star.
- When printing a formula using Spin's LTL syntax, we don't
double-quote complex atomic propositions (that was not valid
Spin input anyway). For instance F"foo == 2" used to be
output as <>"foo == 2". We now output <>(foo == 2) instead.
The latter syntax is understood by Spin 6. It can be read
back by Spot in lenient mode (see above).
- The gspn-ssp benchmark has been removed.
We are pleased to announce the release of Spot 0.9.2.
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 maintenance release includes minor bug fixes and speed
improvements, and adds an interface to ltl3ba on the online
translator.
You can find the new release here:
http://spot.lip6.fr/dl/spot-0.9.2.tar.gz
A more detailed list of new features follows.
New in spot 0.9.2 (2012-07-02):
* New features to the web interface.
- It can run ltl3ba (Babiak et al., TACAS'12) where available.
- "a loading logo" is displayed when result is not instantaneous.
* Speed improvements:
- The unicity hash table of BuDDy has been separated separated
node table for better cache-friendliness. The resulting speedup
is around 5% on BDD-intensive algorithms.
- A new BDD operation, called bdd_implies() has been added to
BuDDy to check wether one BDD implies another. This benefits
mostly the simulation and degeneralization algorithms of Spot.
- A new offline implementation of the degeneralization (which
had always been performed on-the-fly so far) available. This
especially helps the Safra complementation.
* Bug fixes:
- The CGI script running for ltl2tgba.html will correctly timeout
after 30s when Spot's translation takes more time.
- Applying WDBA-minimization on an automaton generated by the
Couvreur/LaCIM translator could lead to an incorrect automaton
due to a bug in the definition of product with symbolic
automata.
- The Makefile.am of BuDDy, LBTT, and Spot have been adjusted to
accomodate Automake 1.12 (while still working with 1.11).
- Better error recovery when parsing broken LTL formulae.
- Fix errors and warnings reported by clang 3.1 and the
upcoming g++ 4.8.
--
Alexandre Duret-Lutz
