* python/spot/__init__.py: Handle 'dicho' option in 'sat_minimize'.
* spot/priv/satcommon.cc: Implement get_number_of_distinct_vals.
* spot/priv/satcommon.hh: Declare get_number_of_distinct_vals.
* spot/twaalgos/dtbasat.cc: Use get_number_of_distinct_vals.
* spot/twaalgos/dtbasat.hh: Change dichotomy function's prototype.
* spot/twaalgos/dtwasat.cc: Use get_number_of_distinct_vals.
* spot/twaalgos/dtwasat.hh: Change dichotomy function's prototype.
Handle options.
* spot/twaalgos/postproc.cc: Handle options.
* spot/twaalgos/postproc.hh: Add dicho_langmap_ var for options.
* tests/core/satmin2.test: Add tests for dichotomy.
* tests/core/satmin.test: Add tests for dichotomy.
* tests/python/satmin.py: Replace 'dichotomy' with 'dicho' option.

* bin/autfilt.cc: Add that option.
* tests/core/highlightstate.test: Add test.
* NEWS: Update.

* python/spot/impl.i: Add python bindings.
* spot/twaalgos/langmap.cc: Implement algo.
* spot/twaalgos/langmap.hh: Declare algo.
* spot/twaalgos/Makefile.am: Add new files.
* tests/python/langmap.py: Add tests.
* NEWS: Update.

* python/spot/__init__.py: Add 'assume' option.
* spot/misc/satsolver.cc: Add function to handle assumptions.
* spot/misc/satsolver.hh: Declare assumption function.
* spot/twaalgos/dtbasat.cc: Implement dtba_sat_minimize_assume.
* spot/twaalgos/dtbasat.hh: Declare it.
* spot/twaalgos/dtwasat.cc: Implement dtwa_sat_minimize_assume and
handle options.
* spot/twaalgos/dtwasat.hh: Declare it.
* spot/twaalgos/postproc.cc: Handle options.
* spot/twaalgos/postproc.hh: Use param_ var for incr and assume.
* tests/core/satmin.test: Add tests for the new function.
* tests/core/satmin2.test: Add tests for the new function.
* tests/python/satmin.py: Add tests for the new function.

* python/spot/__init__.py: Add 'incr' boolean argument.
* spot/twaalgos/dtbasat.cc: Implement dtba_sat_minimize_incr(...).
* spot/twaalgos/dtbasat.hh: Declare it.
* spot/twaalgos/dtwasat.cc: Implement dtwa_sat_minimize_incr(...) and
deal with options.
* spot/twaalgos/dtwasat.hh: Declare it.
* spot/twaalgos/postproc.cc: Add option --sat-minimize=incr.
* spot/twaalgos/postproc.hh: Add incr parameter.
* tests/core/satmin.test: Add tests for incremental version.
Update expected result.
* tests/core/satmin2.test: Add tests for incremental version.
* tests/python/satmin.py: Add tests for incremental version.

* spot/misc/satsolver.hh: Make solver return vector<bool> instead of
vector<int>.
* spot/misc/satsolver.cc: Update code.
* spot/priv/Makefile.am: Add satcommon.*
* spot/priv/satcommon.hh: Declare helper class and factorize some
duplicate code of dt*asat.cc
* spot/priv/satcommon.cc: Implement helper class and factorize some
duplicate code of dt*asat.cc
* spot/twaalgos/dtbasat.cc: Declare helper, implement some functions
in dict struct and update code.
* spot/twaalgos/dtwasat.cc: Declare helper, implement some functions
in dict struct and update code.
* tests/core/readsat.cc: Update tests.
* tests/core/satmin.test: Typo.
* tests/core/satmin2.test: Update an expected result.

* spot/twaalgos/dtbasat.cc: Fix static sat_build.
* spot/twaalgos/dtwasat.cc: Fix static sat_build.

* tests/core/satmin.test: Delete check for SPOT_SATSOLVER env
variable and add state numbers verification.
* tests/core/satmin2.test: Delete check for SPOT_SATSOLVER
env variable.
* tests/python/satmin.py: Delete check for SPOT_SATSOLVER
env variable.

* Makefile.am: Add picosat to subdirs.
* configure.ac: Add picosat/Makefile to AC_CONFIG_FILES.
* README: Add picosat/ in the list of directories.
* debian/copyright: Add picosat licence and details.
* picosat/Makefile.am: Implement Makefile.am in picosat directory.
* spot/Makefile.am: Tell the compiler to add libpico.la into libspot.la.
* picosat/LICENSE: Add picosat licence.
* picosat/NEWS: Add picosat NEWS.
* picosat/VERSION: Add picosat VERSION.
* picosat/picosat.c: Add picosat c file.
* picosat/picosat.h: Add picosat header file.
* spot/misc/satsolver.cc: Update functions.
* spot/misc/satsolver.hh: Add documentation, clean code, change
some functions visibility and separate templates functions.
* spot/twaalgos/dtbasat.cc: Update dtba_to_sat function.
* spot/twaalgos/dtwasat.cc: Update dtwa_to_sat function.

* spot/misc/satsolver.hh: Declare all functions needed.
* spot/misc/satsolver.cc: Implement them.
* spot/twaalgos/dtbasat.cc: Abstract writing.
* spot/twaalgos/dtwasat.cc: Abstract writing.

* .gitignore: Fix typo dt*a instead of dt*ba.

This fix recent failures observed on arch linux because
it uses newer versions of graphviz and Python.

* tests/python/ipnbdoctest.py (sanitize): More substitutions.

* bin/common_setup.cc: Here.

Algorithms that remove transitions can turn a non-deterministic
automaton into a deterministic one, so we need to be able to specify
that determinism can be improved (as opposed to preserved).

* spot/twa/twa.hh (twa::prop_set::improve_det): New attribute.
(twa::prop_keep, twa::prop_copy): Honor it.
* spot/tl/exclusive.cc, spot/twaalgos/alternation.cc,
spot/twaalgos/complete.cc, spot/twaalgos/degen.cc,
spot/twaalgos/determinize.cc, spot/twaalgos/mask.cc,
spot/twaalgos/minimize.cc, spot/twaalgos/remfin.cc,
spot/twaalgos/remprop.cc, spot/twaalgos/sbacc.cc,
spot/twaalgos/sccfilter.cc, spot/twaalgos/simulation.cc,
spot/twaalgos/strength.cc, spot/twaalgos/stutter.cc,
spot/twaalgos/totgba.cc: Adjust calls to prop_keep() and
prop_copy().

* spot/twaalgos/simulation.cc: Reset those to maybe.
* tests/core/semidet.test: Add some tests.

* spot/twa/twa.hh (prop_semi_deterministic): New methods.
* spot/parseaut/parseaut.yy, spot/twaalgos/hoa.cc: Add support for the
semi-deterministic property.
* doc/org/concepts.org, doc/org/hoa.org: Document it.
* spot/twaalgos/isdet.cc,
spot/twaalgos/isdet.hh (is_semi_deterministic): New function.
* bin/autfilt.cc: Add --is-semi-deterministic.
* bin/common_aoutput.cc: Add --check=semi-deterministic.
* tests/core/semidet.test: New file.
* tests/Makefile.am: Add it.
* tests/core/parseaut.test, tests/core/readsave.test: Adjust.

* spot/graph/graph.hh (internal::univ_dest_mapper): New helper class.
* spot/twa/twagraph.cc (merge_univ_dests): Simplify using
univ_dest_mapper.
(purge_unreachable_states, purge_dead_states): Add support for
alternation.
* tests/core/alternating.test: More tests.

* bin/autfilt.cc (ensure_deterministic): Remove alternation on demand.
(process_automaton): Prefer twa::intersects() over
product()/is_empty().
* spot/twa/twa.cc (remove_fin_maybe): Also remove alternation.
* tests/core/alternating.test: More tests.

* bin/autfilt.cc: Implement --is-alternating.
* tests/core/complete.test: Test it.
* NEWS: Mention it.

* bin/autfilt.cc: Implement --is-very-weak.
* tests/core/strength.test: Test it.
* NEWS: Mention it.

and call it after parsing

* spot/twa/twagraph.cc, spot/twa/twagraph.hh
(twa_graph::merge_univ_dests): New method.
* spot/parseaut/parseaut.yy: Call it.
* spot/twaalgos/dot.cc: Improve output, now that
several edges can use the same universal destination.
* tests/core/alternating.test, tests/core/complete.test,
tests/core/parseaut.test, tests/python/_altscc.ipynb,
tests/python/alternating.py, tests/python/alternation.ipynb: Adjust
test case.
* doc/org/tut24.org: Adjust example.

* doc/org/tut23.org, doc/org/tut24.org, doc/org/tut31.org: New files.
* doc/Makefile.am, doc/org/tut.org: Add them.
* doc/org/hoa.org, doc/org/concepts.org: Adjust for alternation support.
* NEWS: Add links.

* spot/twaalgos/remfin.cc: Here.
* tests/core/alternating.test: Add a test case.

* spot/twaalgos/complete.cc: Do not use the initial
state as a sink if it is universal.
* tests/core/complete.test: Add a test case.

* spot/twaalgos/postproc.cc: Call remove_alternation().
* tests/core/alternating.test: Additional test.

* spot/twa/twagraph.hh, spot/twaalgos/are_isomorphic.cc,
spot/twaalgos/canonicalize.cc, spot/twaalgos/couvreurnew.cc,
spot/twaalgos/cycles.cc, spot/twaalgos/degen.cc,
spot/twaalgos/determinize.cc, spot/twaalgos/isunamb.cc,
spot/twaalgos/isweakscc.cc, spot/twaalgos/mask.hh,
spot/twaalgos/minimize.cc, spot/twaalgos/product.cc,
spot/twaalgos/randomize.cc, spot/twaalgos/sbacc.cc,
spot/twaalgos/sccfilter.cc, spot/twaalgos/simulation.cc:
Throw a runtime_error if the input is alternating.

* bin/ltlcross.cc: Add an alternation-removal pass, and
adjust CSV output.
* doc/org/ltlcross.org: Update.
* tests/core/ltl3dra.test, tests/core/ltl3ba.test: Add more tests.
* tests/Makefile.am: Add tests/core/ltl3ba.test.
* NEWS: Mention it.

This is faster than using the abstract interface, and it also supports
alternating automata.  (This will be tested in the tests for
ltlcross's support for alternating automata.)

* spot/twaalgos/stats.cc (stats_reachable, sub_stats_reachable):
Add code specific to twa_graph_ptr.

* spot/twaalgos/remfin.cc (remove_fin_weak): Ignore unreachable
states.  This caused crashes in the test cases for the
upcoming alternation support in ltlcross.

This mixes the subset construction (for 1-state rejecting SCCs) and
the breakpoint construction (for larger rejecting SCCs).  The
algorithm should probably be rewritten in a cleaner and more efficient
way, but that should do for a first version.  It should be easy to
extend it to support Büchi acceptance (since the breakpoint
construction works for this) when we need it.

* spot/twaalgos/alternation.hh,
spot/twaalgos/alternation.cc (remove_alternation): New function.
* tests/python/alternation.ipynb: New file.
* tests/Makefile.am, doc/org/tut.org: Add it.

* spot/twa/twa.hh: Implement the property.
* spot/parseaut/parseaut.yy, spot/twaalgos/hoa.cc: Add input
and output for it.
* spot/twaalgos/strength.cc,
spot/twaalgos/strength.hh (is_very_weak_automaton): New function.
* tests/core/alternating.test: Add a test for --check=strength
on an alternating automaton.
* tests/core/strength.test, tests/core/parseaut.test: Adjust expected
output.
* NEWS, doc/org/hoa.org, doc/org/concepts.org: Document it.

* spot/twaalgos/sccinfo.cc: Consider universal edges as if they were
existential edges.
* spot/twaalgos/sccinfo.hh: Document that.
* spot/twaalgos/dot.cc: Allow option 's' again, for easy testing.
* tests/core/alternating.test: Adjust tests.
* tests/python/_altscc.ipynb: New file (more tests).
* tests/Makefile.am: Add it.

* spot/parseaut/parseaut.yy (fix_initial_state): Use
spot::internal::outgoing_edge_group to reduce all initial states to a
single one.
* tests/core/parseaut.test: Add more tests.

This should will come handy to implement the convertion from LTL to
alternating automata, and to handle automata with multiple initial
states.

* spot/twaalgos/alternation.hh, spot/twaalgos/alternation.cc: New files.
* spot/twaalgos/Makefile.am: Add them.
* python/spot/impl.i: Add bindings.
* tests/python/alternating.py: Test states_and.

The only missing point is that the HOA parser cannot deal with multiple
universal initial states, as seen in parseaut.test.

* spot/graph/graph.hh (new_univ_dests): New function, extracted from...
(new_univ_edge): ... this one.
* spot/twa/twagraph.hh (set_univ_init_state): Implement using
new_univ_dests.
* spot/twaalgos/dot.cc, spot/twaalgos/hoa.cc, python/spot/impl.i:
Add support for universal initial states.
* spot/parseaut/parseaut.yy: Add preliminary support for
universal initial states.  Multiple universal initial states
are still not supported.
* tests/core/alternating.test, tests/core/parseaut.test,
tests/python/alternating.py: Adjust tests and exercise this new feature.

* spot/twaalgos/dot.cc: Handle universal destinations.
Ignore option 's' for alternating automata.
* tests/core/alternating.test: New file.
* tests/Makefile.am: Add it.

Currently this only reads universal branches.  The parser (and the
automaton code) do not support universal initial states.

* spot/parseaut/parseaut.yy: Read universal branches.  Deal with
the no-univ-branch/!univ-branch change in HOA 1.1.
* tests/python/alternating.py: Read the output of print_hoa.
* tests/core/parseaut.test: Adjust test output, and add more tests.

* spot/twaalgos/hoa.cc: Implement it.
* tests/python/alternating.py: Test it.