Update NEWS and documentations
* NEWS: Update. * doc/org/satmin.org: Update satmin page. * bin/man/spot-x.x: Document SPOT_XCNF and edit SPOT_SATSOLVER. * bin/spot-x.cc: Update satmin options. * bin/autfilt.cc: Update satmin related documentations. * bin/man/autfilt.x: Update autfilt options.
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Alexandre GBAGUIDI AISSE
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@ -4,6 +4,11 @@
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#+SETUPFILE: setup.org
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#+HTML_LINK_UP: tools.html
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#+NAME: version
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#+BEGIN_SRC sh :exports none
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head -n 1 ../../picosat/VERSION | tr -d '\n'
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#+END_SRC
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This page explains how to use [[file:ltl2tgba.org][=ltl2tgba=]], [[file:dstar2tgba.org][=dstar2tgba=]], or [[file:autfilt.org][=autfilt=]]
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to minimize deterministic automata using a SAT solver.
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@ -23,8 +28,9 @@ Let us first state a few facts about this minimization procedure.
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3) These two procedures can optionally constrain their output to
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use state-based acceptance. (They simply restrict all the outgoing
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transitions of a state to belong to the same acceptance sets.)
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4) A SAT solver should be installed for this to work. (Spot does not
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distribute any SAT solver.)
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4) Spot distributes a SAT solver, PicoSAT call_version()[:results raw]. This solver was chosen for its performances, simplicity of integration and licence compatible with Spot's one.
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However, it is still possible to use an external SAT solver (as described
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below).
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5) [[file:ltl2tgba.org][=ltl2tgba=]] and [[file:dstar2tgba.org][=dstar2tgba=]] will always try to output an automaton.
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If they fail to determinize the property, they will simply output a
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nondeterministic automaton, if they managed to obtain a
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@ -44,15 +50,11 @@ Let us first state a few facts about this minimization procedure.
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* How to change the SAT solver used
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The environment variable =SPOT_SATSOLVER= can be used to change the
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SAT solver used by Spot. The default is "=glucose -verb=0 -model %I
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>%O=", therefore if you have installed [[http://www.labri.fr/perso/lsimon/glucose/][=glucose= 3.0]] in your =$PATH=,
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it should work right away. Otherwise you may redefine this variable
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to point the correct location or to another SAT solver (for older
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versions of glucose, remove the =-model= option). The =%I= and =%O=
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sequences will be replaced by the names of temporary files containing
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the input for the SAT solver and receiving its output. We assume that
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the SAT solver should follow the conventions of the [[http://www.satcompetition.org/][SAT competition]]
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for input and output.
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SAT solver used by Spot. By default it uses the one distributed with (PicoSAT
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call_version()[:results raw]).
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Here is the expected format of =SPOT_SATSOLVER= : "=<SAT_SOLVER> [options] %I >%O=". The =%I= and =%O= sequences will be replaced by the names of temporary files containing the input for the SAT solver and receiving its output.
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If you have installed the corresponding binary in your =$PATH=, it should work right away. Otherwise you may redefine this variable to point the correct location of the SAT solver.
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We assume that the SAT solver should follow the conventions of the [[http://www.satcompetition.org/][SAT competition]] for input and output.
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* Enabling SAT-based minimization in =ltl2tgba= or =dstar2tgba=
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@ -337,15 +339,35 @@ situations where the tools will produce non-deterministic automata.
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The following options can be used to fine-tune this procedure:
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- =-x tba-det= :: attempt a powerset construction and check if
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there exists a acceptance set such that the
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resulting DTBA is equivalent to the input
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- =-x sat-minimize= :: enable SAT-based minimization. By default it
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tries to reduce the size of the automaton one state at a time.
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This option implies =-x tba-det=.
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- =-x sat-minimize=2= :: enabled SAT-based minimization, but perform a
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dichotomy to locate the correct automaton size. Use this only if
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you suspect that the optimal size is far away from the input
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size. This option implies =-x tba-det=.
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there exists an acceptance set such that the
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resulting DTBA is equivalent to the input.
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- =-x sat-minimize= :: enable SAT-based minimization. It is the same as
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=-x sat-minimize=1= (which is the default value). It performs a dichotomy
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to find the correct automaton size.This option implies =-x tba-det=.
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- =-x sat-minimize=[2|3]= :: enable SAT-based
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minimization. Let us consider each intermediate automaton as a =step=
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towards the minimal automaton and assume =N= as the size of the starting
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automaton. =2= and =3= have been implemented with the aim of not
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restarting the encoding from scratch at each step. To do so, both restart
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the encoding after =N-1-(sat-incr-steps)= states have been won. Now,
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where is the difference? They both start by encoding the research of the
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=N-1= step and then:
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- =2= uses PicoSAT assumptions. It adds =sat-incr-steps= assumptions
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(each of them removing one more state) and then checks direclty the
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=N-1-(sat-incr-steps)= step. If such automaton is found, the process is
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restarted. Otherwise, a binary search begins between =N-1= and
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=N-1-sat-incr-steps=. If not provided, =sat-incr-steps= default value
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is 6.
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- =3= checks incrementally each =N-(2+i)= step, =i= ranging from =0= to
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=sat-incr-steps=. This process is fully repeated until the minimal
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automaton is found. The last SAT problem solved correspond to the
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minimal automaton. =sat-incr-steps= defaults to 2.
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Both implies =-x tba-det=.
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- =-x sat-minimize=4= :: enable SAT-based minimization. It tries to reduce the
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size of the automaton one state at a time. This option implies
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=-x tba-det=.
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- =-x sat-incr-steps=N= :: set the value of =sat-incr-steps= to N. It doest not
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make sense to use it without =-x sat-minimize=2= or =-x sat-minimize=3=.
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- =-x sat-acc=$m$= :: attempt to build a minimal DTGBA with $m$ acceptance sets.
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This options implies =-x sat-minimize=.
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- =-x sat-states=$n$= :: attempt to build an equivalent DTGBA with $n$
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@ -666,6 +688,13 @@ $txt
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[[file:autfiltsm8.png]]
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By default, the SAT-based minimization tries to find a smaller automaton by
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performing a binary search starting from =N/2= (N being the size of the
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starting automaton). After various benchmarks, this algorithm proves to be the
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best. However, in some cases, other rather similar methods might be better. The
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algorithm to execute and some other parameters can be set thanks to the
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=--sat-minimize= option.
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The =--sat-minimize= option takes a comma separated list of arguments
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that can be any of the following:
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@ -679,9 +708,33 @@ that can be any of the following:
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so the output might be smaller nonetheless). If this option is
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used the SAT-based procedure is just used once to synthesize
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one automaton, and no further minimization is attempted.
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- =dichotomy= :: instead of looking for a smaller automaton starting
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from =N=, and then checking =N-1=, =N-2=, etc., do a binary
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search starting from =N/2=.
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- =sat-incr=[1|2]= :: =1= and =2= correspond respectively to
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=-x sat-minimize=2= and =-x sat-minimize=3= options.
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They have been implemented with the aim of not restarting the
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encoding from scratch at each step - a step is a minimized intermediate
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automaton. To do so, both restart the encoding after
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=N-1-(sat-incr-steps)= states have been won - =N= being the size of the
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starting automaton. Now, where is the difference? They both start by
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encoding the research of the =N-1= step and then:
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- =1= uses PicoSAT assumptions. It adds =steps= assumptions (each of
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them removing one more state) and then checks direclty the
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=N-1-(sat-incr-steps)= step. If such automaton is found, the process is
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restarted. Otherwise, a binary search begins between =N-1= and
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=N-1-sat-incr-steps=. If not provided, =sat-incr-steps= defaults to 6.
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- =2= checks incrementally each =N-(2+i)= step, =i= ranging from =0= to
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=sat-incr-steps=. This process is fully repeated until the minimal
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automaton is found. The last SAT problem solved correspond to the
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minimal automaton. =sat-incr-steps= defaults to 2.
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Both implies =-x tba-det=.
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- =sat-incr-steps=N= :: set the value of =sat-incr-steps= to =N=.
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This is used by =sat-incr= option.
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- =sat-naive= :: use the =naive= algorithm to find a smaller automaton. It starts
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from =N= and then checks =N-1=, =N-2=, etc. until the last successful
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check.
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- =sat-langmap= :: Find the lower bound of default sat-minimize procedure. This
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relies on the fact that the size of the minimal automaton is at least equal
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to the total number of different languages recognized by the automaton's
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states.
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- =colored= :: force all transitions (or all states if =-S= is used)
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to belong to exactly one acceptance condition.
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@ -802,6 +855,7 @@ The generated CSV file use the following columns:
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- system time for encoding the SAT problem
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- user time for solving the SAT problem
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- system time for solving the SAT problem
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- automaton produced
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Times are measured with the times() function, and expressed
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in ticks (usually: 1/100 of seconds).
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