* src/ltlvisit/reduce.cc (reduce_visitor): Move ...
* src/ltlvisit/simplify.cc (simplify_visitor): ... here, and
adjust to use the new ltl_simplifier_options.
* src/ltlvisit/reduce.cc (reduce): Use ltl_simplifier
to perform the work of reduce_visitor.  Eventually we want to
get rid of reduce.cc.
* src/ltlvisit/reduce.hh (reduce): Remove the
syntactic_implication_cache used as third argument.

* src/ltltest/kind.test: More pure eventualities and purely
universal properties are detected.

* src/ltlvisit/basicreduce.cc: Do not test
for things like X(true), F(false), or `a U 1`.
These are all trivial identities.

* src/ltlast/binop.cc (binop::binop): Generalize detection
of pure eventualities and purely universal formulae.  E.g.
`f U g' is a pure eventuality if g is a pure eventuality
(regardless of f) or if g is 1.
* src/ltlast/unop.cc (unop::unop): Compute is.eventual
and is.universal for Not.
* src/ltltest/kind.test: Adjust.

It is limited to negative_normal_form_visitor for now.

* src/ltlvisit/simplify.cc, src/ltlvisit/simplify.hh: New files.
* src/ltlvisit/Makefile.am: Add them.
* src/ltlvisit/nenoform.cc, src/ltlvisit/nenoform.hh: Rewrite
using ltl_simplifier.

* src/tgbatest/randpsl.test: Run without valgrind, it is too
slow otherwise.

I.e., SERE without star, or LTL formula using only X and Boolean
operators.

* src/ltlast/formula.hh, src/ltlast/formula.cc: Add a bit for
tracking finite formulas.
* src/ltlast/atomic_prop.cc, src/ltlast/automatop.cc,
src/ltlast/bunop.cc, src/ltlast/constant.cc, src/ltlast/formula.cc:
Adjust.
* src/ltlast/unop.cc, src/ltlast/binop.cc: Adjust and use that
bit to refine the computation of some LTL classes.
* src/ltltest/kind.test: New tests.

These are safety, guarantee, obligation, persistence, and recurrence.

* src/ltlast/formula.hh, src/ltlast/formula.cc: Declare a bit for
each of these classes.
* src/ltlast/atomic_prop.cc, src/ltlast/constant.cc,
src/ltlast/automatop.cc, src/ltlast/binop.cc, src/ltlast/bunop.cc,
src/ltlast/unop.cc: Update these bits.
* src/ltltest/kind.test: Update tests and add more.

* src/ltlast/multop.cc (multop::instance): Implement
the rewriting.   "a:b:c[*]:d:e" becomes "{{a&&b}&c[*]}:{d&&e}".
* src/ltlast/multop.hh: Document it.
* src/ltltest/equals.test, src/ltltest/kind.test: Add test cases.

* src/ltlast/binop.cc (EConcat, UConcat): Rewrite "{b}<>-> f"
as "b && f", and rewrite "{b}[]->f" as "b->f".
* src/ltlast/binop.hh (binop::instance): Document trivial
identities for <>-> and []->.
* src/ltlast/multop.cc (multop::instance): Rewrite "b1 & b2"
as "b1 && b2" when b1 and b2 are Boolean.
(multop::multop): Always disable is.boolean for AndNLM.
* src/ltlast/multop.hh: Document the rewriting.
* src/ltltest/equals.cc: Show the two formulas if the exit_code
is 1, to help debugging.
* src/ltltest/equals.test: Add more tests.
* src/ltltest/kind.test: Adjust tests.

* src/ltlvisit/randomltl.cc (random_formula::update_sums): Remove
duplicate semicolon.

* src/ltlvisit/contain.cc (recurse, reduce_tau03): Do not
run on non-PSL formulae.
* src/ltlvisit/reduce.cc (reduce_visitor::visit): Skip
multop::Fusion operators, and do not run syntactic_implication_neg
on SERE formulae.
* src/ltlvisit/syntimpl.cc (inf_right_recurse_visitor::visit):
Skip [*0].

* src/ltlast/atomic_prop.cc, src/ltlast/automatop.cc,
src/ltlast/binop.cc, src/ltlast/bunop.cc, src/ltlast/constant.cc,
src/ltlast/formula.cc, src/ltlast/formula.hh,
src/ltlast/multop.cc, src/ltlast/unop.cc: Add a bit is.sere_formula
to track SEREs, and fix tracking of PSL formulae.
* src/ltltest/kind.test: Adjust.

* src/ltlparse/ltlscan.ll: Recognize }!.  Also remove
five duplicate rules.
* src/ltlparse/ltlparse.yy: Build {r}<>->1 when parsing {r}!.
* src/ltlvisit/tostring.cc: Print {r}! instead of {r}<>->1.
* src/ltltest/tostring.test, src/ltltest/equals.test:
Add more tests.

* src/ltlast/bunop.hh, src/ltlast/multop.hh: Reorder some comments.

We still don't have any PSL-specific reductions, but at least
the LTL reduction now appear to work on PSL formulas.

* src/ltlvisit/basicreduce.cc (basic_reduce_visitor): Fix the
call to std::copy to handle Concat, Fusion, and AndNLM.
* src/ltlvisit/reduce.cc (reduce_visitor): Fix handling
of UConcat, EConcat, and EConcatMarked.
* src/tgbatest/randpsl.test: Activate reductions.
* src/ltltest/reducpsl.test: New file.
* src/ltltest/Makefile.am (TESTS): Add it.

* src/ltlvisit/randomltl.hh (random_formula::~random_formula):
Declare as virtual.

* src/tgbatest/randpsl.test: New file.
* src/tgbatest/Makefile.am (TESTS): Add it.

* src/tgbaalgos/ltl2tgba_fm.cc (ratexp_trad_visitor::visit):
Use a different translating rule for E* if E accepts [*0].
* src/tgbatest/ltl2tgba.test: Add test case.

* src/ltlvisit/randomltl.cc, src/ltlvisit/randomltl.hh:
(random_boolean, random_sere, random_psl): Add new classes.
* src/ltltest/randltl.cc: Add options to support the above.
Nore: the -p option was renamed to -pL for consistency, but
it is still understood.

* src/ltlvisit/tostring.hh, src/ltlvisit/tostring.cc (to_string):
Add third option to enable formating suitable for SERE.

* src/ltlparse/ltlparse.yy (rationalexp): Allow ->, <->, and xor,
in rational expressions as long as they apply only to Boolean
formulae.
* src/tgbaalgos/ltl2tgba_fm.cc (ratexp_trad_visitor): Adjust
assert in handling of unop::Not.

* src/ltlast/bunop.cc (bunop::bunop): Ensure it using an assert.

* src/ltlvisit/randomltl.hh (random_ltl): Split this class into...
(random_formula, random_ltl): ... these.
* src/ltlvisit/randomltl.cc: New

* src/ltlvisit/syntimpl.hh (syntactic_implication,
syntactic_implication_neg): Move as member of ...
(syntactic_implication_cache): ... this new class, that holds
a cache of results to speedup these functions.
* src/ltlvisit/syntimpl.cc: Adjust to use (lookup, populate,
and cleanup) the cache.
* src/ltltest/syntimpl.cc: Likewise.
* src/ltlvisit/reduce.hh (reduce): Take an optional
syntactic_implication_cache parameter.
* src/ltlvisit/reduce.cc: Adjust to use a
syntactic_implication_cache.
* src/ltltest/equals.cc: Call dump_instances() to help debugging.

* src/ltlvisit/nenoform.cc, src/ltlvisit/lunabbrev.cc,
src/ltlvisit/simpfg.cc, src/ltlvisit/tunabbrev.cc: Do not recurse
if the formula properties indicate that it is already in the right
form.

* src/ltlast/unop.cc (NegClosure): Reset is.not_marked.
* src/ltlvisit/mark.hh,
src/ltlvisit/mark.cc (has_mark_visitor, has_mark): Remove.
* src/tgbaalgos/ltl2tgba_fm.cc: Use f->is_marked() instead
of has_mark(f).

They are too slow.

* src/ltlast/formula.hh (opkind, kind, kind_): Use an enum
to indicate the actual kind of the formula.  This way we can
check the kind of a formula without relying on dynamic_cast.
* src/ltlast/atomic_prop.cc, src/ltlast/automatop.cc,
src/ltlast/binop.cc, src/ltlast/bunop.cc, src/ltlast/constant.cc,
src/ltlast/multop.cc, src/ltlast/refformula.cc,
src/ltlast/refformula.hh, src/ltlast/unop.cc: Adjust constructors.
* src/ltlvisit/basicreduce.cc, src/ltlvisit/mark.cc,
src/ltlvisit/reduce.cc, src/ltlvisit/syntimpl.cc,
src/ltlvisit/tostring.cc: Replace all dynamic_cast by a
call to kind() followed by a static_cast.

* src/ltlast/formula.hh (formula::accepts_eword): New method.
(formula::is.accepting_eword): New flag.
* src/ltlast/formula.cc (print_formula_props): Display the new
property.
* src/ltlast/atomic_prop.cc, src/ltlast/automatop.cc,
src/ltlast/binop.cc, src/ltlast/bunop.cc, src/ltlast/constant.cc,
src/ltlast/multop.cc, src/ltlast/unop.cc: Update
is.accepting_eword as appropriate.
* src/ltltest/consterm.cc, src/tgbaalgos/ltl2tgba_fm.cc: Adjust to
use accepts_eword().
* src/ltlvisit/consterm.cc, src/ltlvisit/consterm.hh: Delete.
* src/ltlvisit/Makefile.am: Remove these files.

This bitfield is easily updated as the formulae are constructed.
Doing so avoids many AST recursions to compute these properties
individually.  This patch removes the eventual_universal_visitor,
as well as the kind_of() function.

* src/ltlast/formula.hh (is_boolean, is_sugar_free_boolean,
is_in_nenoform, is_X_free, is_sugar_free_ltl,
is_ltl_formula, is_eltl_formula, is_psl_formula, is_eventual,
is_universal, is_marked): New methods to query formula
properties in constant time.
(get_props, ltl_prop): A method and structure for
implementation as a field bit in an unsigned, for fast
computation.
(print_formula_props): New function.
* src/ltlast/formula.cc (print_formula_props): Implement it.
* src/ltlast/atomic_prop.cc, src/ltlast/binop.cc,
src/ltlast/bunop.cc, src/ltlast/constant.cc, src/ltlast/multop.cc,
src/ltlast/unop.cc, src/ltlast/automatop.cc: Compute the
properties as instances are constructed.
* src/ltlparse/ltlparse.yy: Update to use is_boolean() instead
of kind_of().
* src/ltltest/kind.cc: Update to use print_formula_props().
* src/ltltest/kind.test: Adjust to test eventual and universal
properties.
* src/ltlvisit/kind.cc, src/ltlvisit/kind.hh: Delete these files.
* src/ltlvisit/Makefile.am: Remove kind.hh and kind.cc.
* src/ltlvisit/reduce.cc (recurse_eu, eventual_universal_visitor):
Remove, no longer needed.
(reduce_visitor, is_eventual, is_universal): Adjust to
use formula::is_eventual(), and formula::is_universal().
* src/ltlvisit/reduce.hh (is_eventual, is_universal): Declare as
deprecated.

* src/ltlast/binop.cc (binop::instance): Simplify fUf, fRf, fWf,
and fRF.
* src/ltlast/binop.hh: Document it.
* src/ltltest/equals.test: Add new tests for 'Exp U Exp'
and 'Exp R Exp', and all missing tests for W and M.

* src/ltlast/unop.hh, src/ltlast/unop.cc: Replace the
simplification by an assert.

The new rewriting are (Exp => Exp) = 1, (Exp <=> Exp) == 1,
and (Exp ^ Exp) == 0.

* src/ltlast/binop.hh: Fix documentation.
* src/ltlast/binop.cc: Fix implementation.
* src/ltltest/equals.test: More tests.
* src/tgbatest/emptchk.test: Remove a useless test.

* src/ltlparse/ltlscan.ll: Handle p=0Wq=1 and p=0Mq=1 in
the same way as we did for
* src/ltltest/parse.test: More tests.

* src/ltlparse/ltlscan.ll (OP_SQBKT_SEP): Accept ":" and "to"
in addition to ".." and ",".
(OP_UNBOUNDED): Recognize "$" for the rule below.
* src/ltlparse/ltlparse.yy: Accept [OP1:$] as a synonym
for [OP1:], for people used to SVA's syntax.
* src/ltltest/equals.test: Test these syntaxes.

* src/tgbaalgos/ltl2tgba_fm.cc (ratexp_trad_visitor): Take a
"negated" parameter and use it.

* src/ltlvisit/consterm.cc: Stop the recursion on [->] and [=].