source: vis_dev/vis-2.1/share/help/check_invariantCmd.txt @ 12

  check_invariant - check all states reachable in flattened network satisfy
  specified invariants
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   check_invariant [-c] [-d <dbg_level>] [-g <hints_file>] [-f] [-h] [-i]
   [-m]   [-r]   [-t   <time_out_period>]   [-v   <verbosity_level>]  [-A
   <reachability_analysis_type>] [-D] <invar_file>

   Performs  invariant  checking  on  a flattened network. Before calling
   this  command,  the user should have initialized the design by calling
   the command [1]init_verify.

   If  the  option  -A3 (abstraction refinement method GRAB) is used, the
   command  [2]build_partition_maigs  should  also  have  been  executed.
   However,  in  this case, the default BDD manager and network partition
   are  not  mandatory,  though they will be used if available. (In other
   words,  the  user  must  run  the  commands  [3]flatten_hierarchy  and
   [4]build_partition_maigs,   but  doesn't  have  to  run  the  commands
   [5]static_order   and   [6]build_partition_mdds  before  calling  this
   command.)  For  extremely large networks, it is actually favorable not
   to  build  them  for the entire concrete model, but let this procedure
   assign bdd ids and construct the partition incrementally.

   Option   -A4  means  abstraction  refinement  approach  using  puresat
   algorithm, which is entirely based on SAT solver.

   An invariant is a set of states. Checking the invariant is the process
   of  determining  that all states reachable from the initial states lie
   in the invariant.

   One way of defining an invariant is through a CTL formula which has no
   path  operators.  Such  formulas  should  be  specified  in  the  file
   invar_file. Note that the support of any wire referred to in a formula
   should  consist  only  of  latches.  For  the  precise  syntax  of CTL
   formulas, see the [7]VIS CTL and LTL syntax manual.

   check_invariant  ignores  all  fairness conditions associated with the
   FSM.

   check_invariant  involves reachability analysis where at every step of
   the  reachability computation all the specified invariants are checked
   in  the reachable states computed thus far. If some invariant does not
   hold,  a  proof  of  failure  is demonstrated. This consists of a path
   starting from an initial state to a state lying outside the invariant.
   This path is made as short as possible. For the -A 0 option or default
   -A  option,  it  is  the  shortest path leading to a state outside the
   invariant.  If  a  set of invariants is specified, the failed formulas
   are reported as soon as they are detected. The check is continued with
   the remaining invariants.

   Command options:

   -d <dbg_level>
          Specify the amount of debugging performed when the system fails
          a formula being checked.

          dbg_level must be one of the following:

          0 : No debugging performed. This is the default.

          1  :  Generate  a  path  from an initial state to a state lying
          outside  the invariant. This option stores the onion rings just
          as  specifying  -f would have. Therefore, it may take more time
          and  memory  if the formula passes. This option is incompatible
          with -A 2 option.

   -f
          Store  the set of new states (onion rings) reached at each step
          of  invariant.  This  option  is  likely to use more memory but
          possibly  faster  results  for invariants that fail. Therefore,
          the debug information for a failed invariant, if requested, may
          be  provided  faster.  This  option is not compatible with -A 2
          options.

   -g <hints_file>
          Use  guided  search.  The  file hints_file contains a series of
          hints.  A  hint is a formula that does not contain any temporal
          operators,  so  hints_file  has  the  same  syntax as a file of
          invariants  used for check_invariant. The hints are used in the
          order  given  to change the transition relation. The transition
          relation   is   conjoined   with   the   hint   to   yield   an
          underapproximation of the transition relation. If the hints are
          cleverly   chosen,   this   may   speed   up   the  computation
          considerably,  because  a  search  with  the changed transition
          relation  may  be  much  simpler  than  one  with  the original
          transition  relation,  and  results  obtained can be reused, so
          that  we  may  never  have  to  do an expensive search with the
          original  relation.  See  also:  Ravi  and  Somenzi,  Hints  to
          accelerate  symbolic  traversal.  CHARME'99;  Bloem,  Ravi, and
          Somenzi,  Efficient  Decision  Procedures for Model Checking of
          Linear Time Logic Properties, CAV'99; Bloem, Ravi, and Somenzi,
          Symbolic  Guided  Search  for  CTL Model Checking, DAC'00. This
          option  is  not compatible with -A 2 option. The description of
          some  options  for  guided search can be found in the help page
          for print_guided_search_options.

   -h
          Print the command usage.

   -c
          Use  the  formula tree so that subformulae are not shared among
          the  CTL  formulae  in the input file. This option is useful in
          the  following scenario - formulae A, B and C are being checked
          in  order  and there is sub-formula sharing between A and C. If
          the  BDDs  corresponding to the shared sub-formula is huge then
          computation  for  B  might  not be able to finish without using
          this option.

   -i
          Print  input  values  causing transitions between states during
          debugging. Both primary and pseudo inputs are printed.

   -m
          Pipe debugger output through the UNIX utility more.

   -r
          Reduce  the FSM derived from the flattened network with respect
          to  each  of  the invariants in the input file. By default, the
          FSM   is  reduced  with  respect  to  the  conjunction  of  the
          invariants  in the input file. If this option is used and don't
          cares  are  being  used  for  simplification,  then  subformula
          sharing is disabled (result might be incorrect otherwise).

          The  truth  of  an invariant may be independant of parts of the
          network   (such   as  when  wires  have  been  abstracted;  see
          [8]flatten_hierarchy). These parts are effectively removed when
          this  option  is  invoked;  this  may  result in more efficient
          invariant checking.

   -t <timeOutPeriod>
          Specify  the  time  out  period  (in  seconds)  after which the
          command aborts. By default this option is set to infinity.

   -v <verbosity_level>
          Specify  verbosity  level.  This sets the amount of feedback on
          CPU usage and code status.

          verbosity_level must be one of the following:

          0 : No feedback provided. This is the default.

          1 : Feedback on code location.

          2 : Feedback on code location and CPU usage.

   -A <reachability_analysis_type>
          This  option  allows  specification of the type of reachability
          computation.

          0:  (default) Breadth First Search. No approximate reachability
          computation.

          1:  High Density Reachability Analysis (HD). Computes reachable
          states  in  a manner that keeps BDD sizes under control. May be
          faster than BFS in some cases. For larger circuits, this option
          could  compute  more  reachable states than the -A 0 option for
          the  same  memory  constraints,  consequently  may  prove  more
          invariants  false. For help on controlling options for HD, look
          up  help  on the command: print_hd_options [9]print_hd_options.
          Refer  Ravi & Somenzi, ICCAD95. The path generated for a failed
          invariant  using this method may not be the shortest path. This
          option is available only when compiled with the CUDD package.

          2.   Approximate   Reachability   Don't  Cares(ARDC).  Computes
          over-approximated reachable states in the reachability analysis
          step.  This may be faster than the -A 0 option . The invariants
          are  checked  in the over-approximation. This may produce false
          negatives,  but  these  are resolved internally using the exact
          reachable  states.  The  final results produced are the same as
          those  for  exact  reachable  states.  For  help on controlling
          options    for   ARDC,   look   up   help   on   the   command:
          print_ardc_options.  [10]print_ardc_options  Refer  2 papers in
          TCAD96 Dec. Cho et al, one is for State Space Decomposition and
          the  other  is  for  Approximate  FSM Traversal. This option is
          incompatible with -d 1 and -g options.

          3.   The  GRAB  Abstraction  Refinement  Method.  Conducts  the
          reachability  analysis  on an abstract model. If the invariants
          are  true  in  the  abstract  model,  they are also true in the
          original  model.  If  the  invariants  are  false, the abstract
          counter-examples  are  used to refine the abstract model (since
          it  is  still  inconclusive).  This  procedure iterates until a
          conclusive  result  is  reached.  Note  that, with this option,
          "build_partitioned_mdds" and "static_order" does not have to be
          executed  before calling "check_invariants," though the default
          BDD  partition  and  order  will  be reused if available. (When
          checking  extremely  large  models,  skipping  either  or  both
          "static_order"  and "build_partitioned_mdds" can often make the
          verification  much  faster.)  The  grainularity  of abstraction
          refinement also depends on the parameter "partition_threshold",
          which  by  default  is  5000;  one can use the VIS command "set
          partition_threshold  1000" to change its value. For experienced
          users  who  want to fine-tune the different parameters of GRAB,
          please  try  the  test  command  "_grab_test"  ("_grab_test -h"
          prints  out  its  usage  information).  Refer  to  Wang et al.,
          ICCAD2003  and  ICCD2004  for  more  information about the GRAB
          algorithm.  Note  that this option is incompatible with the "-d
          1" and "-g" options.

          4.  Abstraction  refinement  approach  using puresat algorithm,
          which  is entirely based on SAT solver. It has several parts: *
          Localization  base Abstraction * K-induction to prove the truth
          of  a  property  *  Bounded  Model  Checking  to  find  bugs  *
          Incremental  concretization  based  methods  to verify abstract
          bugs  *  UNSAT  proof  based  method  to  obtain  refinement  *
          Refinement  minization  to  guarrantee a minimal refinement For
          more  information, please check the BMC'03 and STTT'05 paper of
          Li  et  al.,  "A  satisfiability-based  appraoch to abstraction
          refinement  in  model  checking", and " Abstraction in symbolic
          model  checking  using  satisfiability  as  the  only  decision
          procedure"

   -D
          First  compute  an  overapproximation  to the reachable states.
          Minimize  the transition relation using this approximation, and
          then  compute  the  set  of  reachable states exactly. This may
          accelerate reachability analysis. Refer to the paper by Moon et
          al,  ICCAD98.  The BDD minimizing method can be chosen by using
          "set   image_minimize_method   "   [11]set.   This   option  is
          incompatible with -g.

   -F <dbg_file>
          Write the debugger output to dbg_file.

   <invarFile>
          File containing invariants to be checked.

   Related "set" options:

   rch_simulate <#>
   The  set  option  can be used to set this flag rch_simulate to specify
   the  number  of random vectors to be simulated. Default value for this
   number is 0.

   ctl_change_bracket <yes/no>
   Vl2mv automatically converts "[]" to "<>" in node names, therefore CTL
   parser  does  the  same  thing. However, in some cases a user does not
   want to change node names in CTL parsing. Then, use this set option by
   giving "no". Default is "yes".

   See also command : compute_reach

   -w <node_file> This option invoked the algorithm to generate an error
   trace divided into fated and free segements. Fate represents the
   inevitability and free is asserted when there is no inevitability.
   This can be formulated as a two-player concurrent reachability game.
   The two players are the environment and the system. The node_file is
   given To specify the variables the are controlled by the system.

   -W
   This option represents the case that all input variables are
   controlled by system.

   -G
   We proposed two algorithm to generate segemented counter example. They
   are general and restrcited algorithm. Bu default we use restricted
   algorithm. We can invoke general algorithm with -G option. For more
   information, please check the STTT'04 paper of Jin et al., "Fate and
   Free Will in Error Traces"
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   Last updated on 20050519 10h16

References

   1. file://localhost/projects/development/hsv/vis/common/doc/html/init_verifyCmd.html
   2. file://localhost/projects/development/hsv/vis/common/doc/html/build_partition_maigsCmd.html
   3. file://localhost/projects/development/hsv/vis/common/doc/html/flatten_hierarchyCmd.html
   4. file://localhost/projects/development/hsv/vis/common/doc/html/build_partition_maigsCmd.html
   5. file://localhost/projects/development/hsv/vis/common/doc/html/static_orderCmd.html
   6. file://localhost/projects/development/hsv/vis/common/doc/html/build_partition_mddsCmd.html
   7. file://localhost/projects/development/hsv/vis/common/doc/ctl/ctl/ctl.html
   8. file://localhost/projects/development/hsv/vis/common/doc/html/flatten_hierarchyCmd.html
   9. file://localhost/projects/development/hsv/vis/common/doc/html/print_hd_optionsCmd.html
  10. file://localhost/projects/development/hsv/vis/common/doc/html/print_ardc_optionsCmd.html
  11. file://localhost/projects/development/hsv/vis/common/doc/html/setCmd.html