********************** NuSMV 2.x.x (2003/06/xx) **********************

This is a refactoring version. New types have been defined for Bdd fsm, 
Sexp fsm, Bdd encoding. 

* Trans type "Conjuntive" is no longer supported. It has been
substituted by the type "Threshold"



********************** NuSMV 2.1.1 (2002/11/08) **********************

This is a bug fix release that solves some problems showed by previous
releases.

* Generic
  - fixed a problem in the checking for recursive definitions that
    allowed to parse assignments with dependencies not broken by a
    time delay. (affected file nusmv/src/compile/compileCheck.c)

  - fixed a problem in the encoding that caused NuSMV to exit with an
    error when the BDD dynamic variable ordering was enabled. Many
    thanks to Yunja Choi for the bug report. (affected file
    nusmv/src/compile/compileEncode.c)

* BMC tableau generator
  - fixed a bug in the tableau generator that erroneously ignored
    NuSMV invariants in path of length 0. (affected file
    nusmv/src/bmc/bmcModel.c)

  - improved the performances of the Past LTL tableau generator.
    (affected file nusmv/src/bmc/bmcTableauPLTLformula.c)

* Documentation 
  - improved the user manual. Thanks to Thomas Wahl for signaling us
    the ambiguities. (affected file nusmv/doc/user-man/nusmv.texi)

  - fixed a problem in the on-line documentation of the
    write_boolean_model command. Many thanks to Andrea Fedeli for the
    bug report. (affected file nusmv/src/compile/compileCmd.c)

* Parsing
  - fixed a problem in the lexical analyzer in the parsing of very
    long comments. (affected file src/parser/input.l)

  - not recognized preprocessor macros now cause a parsing error.
    (affected file src/parser/input.l)
  
********************** NuSMV 2.1.0 (2002/07/03) **********************

This is a major release of NuSMV. Several improvements have been done
with respect to NuSMV 2.0. The most relevant are:

* New functionalities

  - Past LTL

    Now LTL properties can also include *past* temporal operators.
    Differently from standard temporal operators, that allow to
    express properties over the future evolution of the FSM, past
    temporal operators allow to characterize properties of the path
    that lead to the current situation. 

    Past LTL temporal operators are supported both in BDD-based Model
    Checking and in Bounded Model Checking of LTL specifications.  The
    extended LTL to SMV tableau translator for the past fragment of LTL
    has been contributed by Ariel Fuxman <afuxman@cs.toronto.edu>.

  - Full Fairness
    
    Now NuSMV supports two types of fairness constraints, namely the
    weak fairness, or "justice", constraints and the strong fairness,
    or "compassion", constraints. 

    A justice constraint consists of a formula f which is assumed to
    be true infinitely often in all the fair paths. A compassion
    constraint consists of a pair of formulas (p,q); if property p is
    true infinitely often in a fair path, then also formula q has to
    be true infinitely often in the fair path. 

    Old versions of NuSMV supports only weak fairness.  In the current
    version of NuSMV, compassion constraints are supported only for
    BDD-based LTL model checking.  The strong fairness model checking
    algorithm for LTL specifications has been contributed by
    Rik Eshuis <eshuis@cs.utwente.nl>.

    We plan to add support for compassion constraints also for CTL
    specifications and in Bounded Model Checking in the next releases
    of NuSMV.

  - ZCHAFF SAT solver

    The new version of NuSMV allows for the usage of the ZCHAFF
    library as the SAT solver in Bounded Model Checking.

    ZCHAFF is a very strong state-of-the-art SAT solver developed by
    the Princeton University. ZCHAFF won the SAT 2002 Competition as
    the Best Complete Solver in both industrial and handmade
    benchmarks categories. ZCHAFF has also shown a consistent speed-up
    in the solution of Bounded Model Checking problems. 

* Architecture

  Several aspects of the NuSMV architecture have been improved.

  - We have improved the management of the Conjunctive Partitioning
    management of transition relations. With respect to old versions
    of NuSMV, the new code is more modular and easier to extend.

  - The Bounded Model Checking code has undergone a general revision.
    In particular:
    - the file organization of the bmc package has been improved
      in order to enhance readability and extensibility;
    - a generic interface to Boolean Expression Managers has been
      added; it is now possible to replace the current manager of
      boolean expressions (RBC) with more advance managers (e.g., BED);
    - a generic interface to SAT solvers gas been defined; this 
      makes it easier to add support for new SAT solvers in NuSMV.
  
* Documentation

  - We have updated the user manual with the new features of NuSMV 2.
    Moreover, we have added to the manual a tutorial that covers
    the basic functionalities on NuSMV.

* Bug fixes

  Several bug fixes and minor enhancements have been done.


********************** NuSMV 2.0.3 (2002/03/27) **********************

- Fixed important bug in the management of the BDD-based 
  representation of the Finite State Machines. This bug
  lead to an assertion failure in the case properties were
  checked using the cone-of-influence reduction.

  Many thanks to Yunja Choi for the bug report.

  (Affected files: nusmv/src/compile/compile.h,compileCmd.c,
  compileStruct.c,compileUtil.c, nusmv/src/prop/propProc.c,
  nusmv/src/sm/smMisc.c)

- Fixed bug in the "reset: routine of the interactive shell.
  The reachable states were not freed during the reset, thus
  leaving garbage information that lead to failures in
  the following commands.
  (Affected files: nusmv/src/sm/smCmd.c)

- Fixed a memory leak in some routines added to the CUDDs to fulfill
  the needs of NuSMV. (Affected files: cudd-2.3.0.1/cudd/cuddAddOp.c,
  cuddBddOp.c)

- Extended printing routines to new operators XOR and XNOR.
  (Affected files: nusmv/src/node/nodePrint.c,nodeWffPrint.c)

- Enhanced CUDD routine that extracts the symbolic representation of BDDs.
  (Affected files: cudd-2.3.0.1/cudd/cuddBddOp.c)

********************** NuSMV 2.0.2 (2002/01/30) **********************

- Fixed important bug in the optimized tableau construction of
  SAT-based Bounded Model Checking engine. This bug lead to an
  "assertion fail" in the verification of formulas "p U q".  
  (Affected files: nusmv/bmc/bmcModel.c)

- Fixed minor bug in main routine of the batch verification: now the
  BDD master FSM is not built in the case of SAT-based Bounded Model
  Checking. This fix permits a substantial gain in performance in the
  case of Bounded Model Checking. (Affected files: nusmv/sm/smMisc.c)

- Disabled printing of memory/cpu statistics under cygwin. This
  fix allows for a clean compilation of NuSMV also on windows
  platforms. (Affected files: cudd-2.3.0.1/util/cpu_stats.c)

- Minor upgrades in the documentation and in the Makefile.

********************** NuSMV 2.0.1 (2001/11/14) **********************

This is a bug fix release that solves a problem occurring on SunOS systems.
Nothing relevant changes in the Linux version.

Many thanks to Rik Eshuis for the bug report.

**********************************************************************
