 news since 3.2.1
--------------------------------------------------------------------------------
+ remove obsolete CL option --smt2-model (use -m --output-format=smt2 instead)

 news for release 3.2.1 since 3.2.0
--------------------------------------------------------------------------------
+ initial version of Dockerfile for Boolector
  (thanks to Andrew V. Jones)
+ fix issue with infinite recursion in Python API
  (thanks to Andrew V. Jones)
+ fix issue with dumping constant arrays
+ fix issue with reset assumptions and checking of failed assumptions
+ fix witness printing in btormc

 news for release 3.2.0 since 3.1.0
--------------------------------------------------------------------------------
+ new dumper CNF printer (enable with CLI option -dd and API option
  BTOR_OPT_PRINT_DIMACS)
+ fix issue with model construction for constant arrays
+ boolector_sat is not automatically called on smt2 input anymore, must be
  explicitly called via (check-sat) in the input file
+ smt2:
  - support for parsing constant arrays
  - support for :global-declarations
+ API changes:
  - boolector_ror and boolector_rol now allow same bit-width for both operands
+ new API calls
  - boolector_roli
  - boolector_rori

 news for release 3.1.0 since 3.0.0
--------------------------------------------------------------------------------
+ build system:
  - requires now cmake >= 3.3
  - exports library interface for using find_package(Boolector) in cmake projects
+ support for custom abort callback function
  (called on abort instead of actually aborting)
+ Python API now throws Python exceptions on abort conditions
  (e.g., when underlying C API is misused)
+ command line options that previously expected integer values denoting enum
  values are now configured with strings denoting the particular modes that
  can be selected; -<opt>=help and --<opt>=help allow to print detailed help
  messages for these modes
+ fixed issue in SMT2 parser to correctly print echo commands
  (thanks to Dominik Klumpp)
+ fixed race condition in Cython dependencies
  (thanks to Marco Gario)
+ patches and documentation for building Boolector on Windows
  (thanks to Andrew V. Jones)
+ support/use termination function feature of CaDiCaL
  (thanks to Andrew V. Jones)
+ various fixes to contrib dependecy scripts
  (thanks to Serge Bazanski)
+ new API calls
  - boolector_copy_sort
  - boolector_min_signed
  - boolector_max_signed
  - boolector_is_bv_const_zero
  - boolector_is_bv_const_one
  - boolector_is_bv_const_ones
  - boolector_is_bv_const_min_signed
  - boolector_is_bv_const_max_signed
+ CaDiCaL is now default SAT engine
+ support for constant arrays
+ support for GMP as bit-vector implementation
+ support for CyproMiniSat
  - supports multi-threading via option --sat-engine-n-threads
+ switched to Google test as testing framework
+ CLI options changed (replaced ':' with a '-')
+ BtorMC improvements (HWMCC'19 version)
  - k-induction engine with simple path constraints
+ Poolector Python script used in SMT-COMP'19

news for release 3.0.0 since 2.4.1
--------------------------------------------------------------------------------
+ new build system, requires cmake >= 2.8
  - setup-*.sh scripts for dependencies (btor2parser, SAT solvers) in contrib
+ support for quantified bit-vectors (BV)
+ new bounded model checker BtorMC
+ support for new format BTOR2
+ support for CaDiCaL as SAT back-end
+ name of the Python module changed to pyboolector
+ SMT2 support for:
  - echo
  - declare-const
  - check-sat-assuming
  - get-unsat-assumptions
  - set-option :produce-unsat-assumptions
  - set-option :produce-assertions
  - set-logic ALL
+ new API calls
  - boolector_constd
  - boolector_consth
  - boolector_copyright
  - boolector_exists
  - boolector_forall
  - boolector_get_failed_assumptions
  - boolector_repeat
  - boolector_pop
  - boolector_push
  - boolector_version
+ removed obsolete API calls
  - boolector_set_sat_solver_lingeling
  - boolector_set_sat_solver_minisat
  - boolector_set_sat_solver_picosat
+ changes in API calls
  - boolector_srl, boolector_sll and boolector_sra now supports operands with
    the same bit-width (SMT-LIB v2 compatible)
+ various improvements and extensions of btormbt

news for release 2.4.1 since 2.4.0
--------------------------------------------------------------------------------
+ sequential portfolio combination of bit-blasting and SLS engine
  (option --fun:presls) analogous to combination with PROP engine
  (option --fun:preprop)
+ fixed: dumping smt2 nodes in incremental mode

news for release 2.4.0 since 2.3.1
--------------------------------------------------------------------------------
+ refactored, extended and improved btormbt
+ new API functions:
  - boolector_is_uf
+ dumping smt2 nodes in incremental mode is now also possible if Boolector
  compiled with assertions
+ fixed another issue with get-value
  (thanks to Praveen Gundaram)
+ refactored model printing
+ command line option changes:
  - --incremental-all -> --incremental-smt1
+ optimized lemma generation of function solver

news for release 2.3.1 since 2.3.0
--------------------------------------------------------------------------------
* fixed an issue with model printing (get-value)
  (thanks to Levent Erkok)

news for release 2.3.0 since 2.2.0
--------------------------------------------------------------------------------
* new QF_BV engines
  + SLS engine
  + PROP engine
  + AIGPROP engine
* fixed an issue with model generation and lambda extraction
  (thanks to Tim Blazytko)
* fixed an issue in boolector_int
  (thanks to Niklas)
* fixed issue with printing BTOR models
* improved and extended option handling
  + boolector_get_opt_val -> boolector_get_opt
* many under-the-hood changes, refactoring, improvements
* API changes:
  + boolector_*_opt* now takes enum BtorOption instead of char* as argument
  + renamed:
     - boolector_get_opt_val -> boolector_get_opt
  + the following functions now take BoolectorSort:
    instead of int as argument:
     - boolector_zero,
     - boolector_ones,
     - boolector_one,
     - boolector_int,
     - boolector_array,
     - boolector_param
  + the following functions now return uint32_t instead of int:
     - boolector_get_width
     - boolector_get_index_width
     - boolector_get_fun_arity
     - boolector_get_opt (was boolector_get_opt_val)
     - boolector_get_opt_min
     - boolector_get_opt_max
     - boolector_get_opt_dflt
  + the following functions now return bool instead of int:
     - boolector_is_const
     - boolector_is_var
     - boolector_is_array
     - boolector_is_array_var
     - boolector_is_param
     - boolector_is_bound_param
     - boolector_is_fun
     - boolector_is_equal_sort
     - boolector_failed
  + the following options now return BtorOption instead of const char *
     - boolector_first_opt
     - boolector_next_opt
* new API functions:
  + boolector_unsigned_int
  + boolector_get_sort
  + boolector_fun_get_domain_sort
  + boolector_fun_get_codomain_sort
  + boolector_match_node_by_symbol
  + boolector_is_array_sort
  + boolector_is_bitvec_sort
  + boolector_is_fun_sort
  + boolector_has_opt
* dumping: new behavior:
  + boolector_dump_* does not simplify the formula before dumping anymore
    (call boolector_simplify prior to dumping explicitely if necessary)
  + when dumping via the CL, the observable dumping behavior did not change
    (formula is simplified prior to dumping)

news for release 2.2.0 since 2.1.1
--------------------------------------------------------------------------------
* refactored a lot of code
  + refactored and extended btormbt
  + refactored and improved array/lambda engine
  + refactored and extended lambda extraction
* removed SMT1 dumper (parsing SMT1 still supported)
* fixed push/pop support in SMT2 with model generation enabled
  (thanks to James Bornholt)
* fixed an issue with model generation (thanks to Mikoláš Janota)
* fixed issues with failed assumptions
* API changes:
    + boolector_get_bits now requires to free returned bit strings via
      boolector_free_bits (analogous to boolector_bv_assignment)
    + removed boolector_dump_smt1 and boolector_dump_smt1_node
    + removed deprecated functions boolector_enable_model_gen,
      boolector_generate_model_for_all_reads, boolector_enable_inc_usage,
      boolector_set_rewrite_level, boolector_set_verbosity,
      boolector_set_loglevel, boolector_get_symbol_of_var

news for release 2.1.1 since 2.0.7
--------------------------------------------------------------------------------
* added support for array extensionality
* added lambda extraction (enabled by default)
* added model based testing tools btormbt and btoruntrace
* reduced memory footprint
* improved performance of cloning
* added support for push/pop in SMT-LIBv2 parser
* added support for :print-success in SMT-LIBv2 parser
* added support for dumping BV formulas in AIGER format (replaces synthebtor)
* API changes/additions:
  + added boolector_fixate_assumptions
  + added boolector_reset_assumptions
  + added boolector_dump_aiger_ascii
  + added boolector_dump_aiger_binary
  + changed boolector_*_sort
    - now takes BoolectorSort instead of BoolectorSort* as arguments
* adpated and updated Python API to support new API
  - Assert(), Assume(), and Failed() now support variable number of arguments


news for release 2.0.7 since 2.0.6
--------------------------------------------------------------------------------
* added option to (en|di)sable use of Boolector exit codes
* fixed help message issues
* fixed option handling issues
* fixed caching bug in model generation
* fixed issues with lambda hashing
* improved SMT dumpers

news for release 2.0.6 since 2.0.5
--------------------------------------------------------------------------------
* fixed printing issues in interactive SMT2 mode
* SMT2 parser now exits immediately after (exit) command was read

news for release 2.0.5 since 2.0.4
--------------------------------------------------------------------------------
* add support for termination callbacks (C and python API)
* smt2 parser: added option :regular-output-channel
* fixed smt2 interactivity issues
* fixed issue in Python API with Python 2.7 compatibility (__div__)
* fixed segmentation fault in SMT2 model printer

news for release 2.0.4 since 2.0.3
--------------------------------------------------------------------------------
* fixed bug in compare function for pointer hashing
* fixed performance issues when computing scores for don't care reasoning
* added smt2 models (get-value, get-model)
* fixed some issues in the Python API (thanks to Ryan Goulden)
* improved dumping of SMT2 formulas

news for release 2.0.3 since 2.0.1
--------------------------------------------------------------------------------
* fixed segmentation fault in back annotation for 'synthebtor'
* reenabled verbosity output for SAT solvers during search
* removed stale empty lines in triple verbose output
* fixed compilation issues with gcc/g++ 4.4

news for release 2.0.1 since 2.0.0
--------------------------------------------------------------------------------
* fixes bug in model generation

news for release 2.0.0 since 1.6.0
--------------------------------------------------------------------------------
* General:
  + Boolector python API
  + cloning support
  + support for uninterpreted functions
  + new improved model generation, supports two modes now:
    - --model-gen=1 or -m:
	generate model for all asserted expressions
	(same as model generation in previous versions)
    - --model-gen=2 or -m -m:
	generate model for all created expressions
  + fixed several rewriting bugs
  + refactored a lot of code
  + new output format for models
* Optimizations:
  + re-enabled and fixed unconstrained optimization
  + don't care reasoning on bit vector skeleton
    - dual propagation optimization
    - justification optimization
* API changes:
  + API functions return node of type BoolectorNode instead of BtorNode
  + new option handling
    + can be set via environment variables
    + set options via boolector_set_opt
  + new options
    - for a complete list of options please refer to the documentation of
      boolector_set_opt
  + deprecated functions:
    - boolector_get_symbol_of_var
      -> use boolector_get_symbol (...)
    the following functions are obsolete with boolector_set_opt
    - boolector_enable_model_gen
      -> use boolector_set_opt ("model_gen", 1)
    - boolector_generate_model_for_all_reads
      -> use boolector_set_opt ("model_gen", 2)
    - boolector_enable_inc_usage
      -> use boolector_set_opt ("incremental", 1)
    - boolector_set_rewrite_level
      -> use boolector_set_opt ("rewrite_level", ...)
    - boolector_set_verbosity
      -> use boolector_set_opt ("verbosity", ...)
    - boolector_set_loglevel
      -> use boolector_set_opt ("loglevel", ...)
  + new API functions to create uninterpreted functions
    - boolector_uf
    - boolector_bool_sort
    - boolector_bitvec_sort
    - boolector_fun_sort
  + limited boolector_sat calls
    - set lemmas on demand limit
    - set conflict limit for SAT solver
* Notes:
  + If uninterpreted functions occur in the formula it is not possible to
    dump the formula to BTOR 1.2 format (this will be fixed with BTOR 2.0).

news for release 1.6.0 since 1.5.119
--------------------------------------------------------------------------------
* extensionality support disabled
* support for macros and lambdas
* model based testing 'btormbt'
* API tracing and untracing with 'btoruntrace'
* improved quality of SMT2 parse error messages
* added missing semantic checks in SMT2 parser

news for release 1.5.119 since 1.5.118
--------------------------------------------------------------------------------
* fixed '{boolector,btor}_set_sat_solver
  (if MiniSAT and/or PicoSAT are not not enabled at compile time)

news for release 1.5.118 since 1.5.116
--------------------------------------------------------------------------------
* '--solver=...' command line option and 'boolector_set_sat_solver'
* delayed Lingeling preprocessing using 'simpdelay'

news for release 1.5.116 since 1.5.115
--------------------------------------------------------------------------------
* examples compilable again
* fixed assertions in 'booolector.c'
* support for new reentrant PicoSAT API (since PicoSAT version 953)

news for release 1.5.115 since 1.5.13
--------------------------------------------------------------------------------
* added 'bvcomp'
* boolean top-level skeleton simplification
* use of 'lglclone' in incremental mode
* added some more rewriting
* removed 3VL code
* removed PrecoSAT, basicbtor
* in-depth, look-ahead, interval
* incremental SMTLIB1 interface
* added MiniSAT support
* rebuilding AIGs / Expressions
* more compact SMTLIB1 parsing
* symbolic lemmas instead of direct CNF encoding
* more compact AIG to CNF translation
* gzip/bzip2/7z compressed input files
* time out option
* SMTLIB 2 support

news for release 1.5.13 since 1.4.1
--------------------------------------------------------------------------------
* new incremental mode for multiple formulas in SMT benchmarks
* integration of MiniSAT
* SMT parser demotes logic if possible
* better control of best suitable solver in main application
* generic incremental SAT glue logic
* integration of Lingeling

news for release 1.4.1 since 1.4
--------------------------------------------------------------------------------
* MacOS port
* disabled unconstrained optimization

news for release 1.4 since 1.3
--------------------------------------------------------------------------------
* hid API change in 'picosat_add' for older version of PicoSAT
* fixed EOF issue reading an empty file from stdin
* removed old license references

news for release 1.3 since 1.2
--------------------------------------------------------------------------------
* first source code release
* fixed a rewriting bug by uncommenting simplification code

news for release 1.2 since 1.1
--------------------------------------------------------------------------------
* improved rewriting
* PrecoSAT now standard solver for non-incremental usage,
  PicoSAT used otherwise

news for release 1.1 since 1.0
--------------------------------------------------------------------------------
* improved handling of unconstrained variables and arrays
* improved rewriting engine
* removed command line switch for refinement limit
* fixed bug where Boolector could report 'unknown' in regular (non-bmc) mode
* fixed minor caching problem on AIG layer
* fixed other bugs

news for release 1.0 since 0.7
--------------------------------------------------------------------------------
* public C API
* documentation and examples
* improved SMT parser (:formula can now be an fvar).

news for release 0.7 since 0.6
--------------------------------------------------------------------------------
* fixed model generation bugs
* improved under-approximation
* added support for bvcomp (SMT-LIB)

news for release 0.6 since 0.5
--------------------------------------------------------------------------------
* fixed model generation bugs
* fixed rewriting bug
* support for new under-approximation techniques

news for release 0.5 since 0.4
--------------------------------------------------------------------------------
* faster model generation
* support for array models
* support for under-approximation techniques for bit-vector variables and reads
