NEWS

Overview of Changes in alpha120
===============================
* fixed memory leak in normalizeTerm() message
* fixed double counting of initial eq rewrites and mb
  application in metaApply()/metaXapply()
* added rule application to the meta-interpreter
* added single step narrowing with variant unification
  to the meta-interpreter
* added narrowing search with variant unification, with
  and without path, to the meta-interpreter

* Overview of Changes in alpha119
================================
* smart load "sload" directive
* more sort computation messages added to the meta-interpreter
* unification and disjoint unification added to the meta-interpreter
* fixed fake rewrites from object-message rewriting that
  were visible in trace/break/profile
* variant generation added to the meta-interpreter
* fixed mb/eq double counting bugs in metaMatch()/metaXmatch()
  and getMatch()/getXmatch()
* variant unifier generation added to the meta-interpreter
* fixed memory leak in metaGetVariant()
* pretty printing added to the meta-interpreter
* parsing added to the meta-interpreter
* fixed physical vs nominal argument index stacking bugs

Overview of Changes in alpha118
===============================
* getSearchResult()/getSearchResultAndPath() messages added to
  meta-interpreter
* -show-pid command line option
* SIGINFO (SIGUSR1 on Linux) now works immediately when blocked
  on sockets rather then waiting for next rewrite
* fixed memory leaks in metaXmatch()
* getMatch()/getXmatch() messages added to meta-interpreter
* upperCase()/lowerCase()  functions added to fmod STRING
* sort computation messages added to the meta-interpreter

Overview of Changes in alpha117
===============================
* fixed syntax error location bug in new parser
* fixed show view bug
* fixed symmetric upView() bug
* fixed showModule bug in the meta-interpreter where imports
  and parameters were omitted
* fixed hang when doing an abort from erewrite
* fixed crash caused by object-message rewriting with the
  set clear rules off command
* fixed bug where rewriteTerm()/frewriteTerm() in the
  meta-interpreter did not reset next rule pointers
* fixed a bug where modules cached by the metalevel functional
  metalevel would be incorrectly used by by the meta-interpreter
* fixed bug where using the functional metalevel from within
  the meta-interpreter would pull imports from object level
  interpreter
* fixed bug where using the ascent functions from within
  the meta-interpreter would pull modules from object level
  interpreter
* added insertView and showView messages to meta-interpreter
* meta-interpreter now supports erewriteTerm message
* erewrite will check for external events even when internal
  rewrites are possible
* fixed memory leak triggered by bad unify command
* loop-mode/pipe edge case reverted to old behavior for IOP
* status report in response to SIGINFO (SIGUSR1 on Linux)

Overview of Changes in alpha116
===============================
* fixed bug in ctor calculations for associative operators;
  enforce new ctor consistancy for such operators
* fixed related bugs in unifier filtering, variant folding
  and narrowing folding wrt the handing of abstraction
  variables
* new mixfix parser based on Leo's algorithm fixes many
  bubble related bugs

Overview of Changes in alpha115
===============================
* fixed bug where show mod command output empty parentheses
* fixed bug where maude wouldn't compile without SMT support
* support for file i/o
* support for standard streams
* support for lexical level QidList <-> String conversion
* no prompting when stdin redirect to read from file
* sort Bound and op unbounded have their own fmod

Overview of Changes in alpha114
===============================
* more sanity checks at object level and meta level
* pretty printer smarter about iterated operator disambiguation
* fixed bug where narrowing attribute was not being printed
  if it was a rule's only attribute
* support for Yices2 as the SMT solver backend
* fixed bug in CVC4 bindings where passing something other than
  a positive integer constant for the second argument to divisible
  produced a crash
* asserting nonlinear stuff in CVC4 now produces unknown rather
  that a crash

Overview of Changes in alpha113
===============================
* redesigned/extended vu narrowing functionality

Overview of Changes in alpha112b
================================
* fixed bug in AU instantiation code introduced by
  optimizations in alpha111b
* fixed memory corruption bug in class VariantUnificationProblem
  where the garbage collector runs before object fully initialized

Overview of Changes in alpha112a
================================
* support for debug, cont, debug cont in vu-narrow
* support for debug, cont, debug cont, incompleteness and
  printing state and timing information in narrow
* support for cont/debug cont in variant unify
* support for cont/debug cont in get variants
* support for debug and debug cont in srewite
* support for debug, cont, debug cont and printing
  printing state and timing information in smt-search
* support for debug and debug cont in search
* fixed longstanding family of related performance bugs
  in the ACU matchers
* added bound element variable ACU stripper-collector automaton
* added early failure optimization for ACU_LazySubproblem

Overview of Changes in alpha112
===============================
* fixed a longstanding bug in the comparison of NatSets that
  amongst other things broke the LTL -> VWAA conversion in the
  model checker

Overview of Changes in alpha111b
================================
* optimized handling of stacks of states in conditions
* optimized construction of free right hand sides
* fixed bug where 0 step rewrites module SMT could return
  unsatisfiable constraints
* fixed bug where bindings were being shared between eager and
  lazy places in both regular narrowing and variant narrowing
* fixed bug where narrowing steps and equational rewrites
  weren't being counted in metaNarrow()
* vu-narrow command added
* metaNarrowingSearch() descent function added
* fixed bug where illegally parameterizing a module by a
  parameterized module caused a crash

Overview of Changes in alpha111a
================================
* fixed bug where variables occuring only in a irreducibility
  constraint could cause a crash
* fixed bug where irreducibility constraint could be ignored
* better handled of contexts for metaNarrowingApply()
* require that variables that only occur in irreducibility
  constraint meet safety criteria

Overview of Changes in alpha111
===============================
* fixed bug where an ambiguity in a term-hook caused crash in
  sort computation because module isn't semi-compiled at this point
* new narrowing descent function
* one of the old narrowing descent functions now supports
  incompleteness

Overview of Changes in Maude 2.7.1 (alpha110b)
==============================================
* fixed typos and copyright date
* minor configuation fixes

Overview of Changes in alpha110a
================================
* fixed bug in ACU unification that was introduced in alpha108

Overview of Changes in alpha110
===============================
* reorganization of unification sort computations
* added -print-to-stderr flag
* added cycle detection and depth bounds to PIG-PUG
* fixed some uninitialized memory reads in SMT code

Overview of Changes in alpha109
===============================
* new metalevel interface for variant narrowing
* large number of finite variant examples from Jose Meseuger added
  to the test suite

Overview of Changes in alpha108a
================================
* fixed bug in variant narrowing where ground terms caused substitution size
  mismatch and memory corruption during subsumption check
* replacement rope library avoids build problems on Mac

Overview of Changes in alpha108
===============================
* new associative unification algorithm based on PIG-PUG
* unification infrastructure support for incomplete algorithms
* fixed bug in metaGetIrredundantVariant()
* fixed bug in variant narrowing where collapse terms were being narrowed
  with variant equations from the wrong kind

Overview of Changes in alpha107
===============================
* fixed bug where asking for the same variant or variant unify twice in
succession from the metalevel resulted in memory corruption

Overview of Changes in alpha106
===============================
* improvements to linear associative unification integration
* fixed bug in SequenceAssignment code (low level associative unification code)

Overview of Changes in alpha105
===============================
* experimental support for multi-step search modulo SMT

Overview of Changes in alpha104
===============================
* fixed duplicate advisories about missing sorts
* fixed missing echoing bug for commands with 2 optional arguments
* fixed caching bug for descent functions
* experimental support for 1-step rewriting modulo SMT

Overview of Changes in alpha103
===============================
* 0/1 is now a valid Rat constant
* advisory printed when downTerm() fails because of kind clash
* experimental support for calling CVC4
* fixed bug where metaPrettyPrint() was failing to generate needed
  disambiguation for built-in data types

Overview of Changes in alpha102
===============================
* experimental support for linear associative unification

Overview of Changes in Maude 2.7 (alpha101)
===========================================
* fixed bug with debug text being output during rewriting
* MVM now supports _==_ and _=/=_
* incementalized (up to layer level) variant narrowing and unification
* --always-advise flag

Overview of Changes in alpha100a
================================
* dlmalloc removed (already disabled on most platforms)
* MVM now supports non-linear variables
* fixed bug with debug text being output during variant narrowing
* (binary) Mac version now compiled with Mac Ports toolchain which
  resolves several issues caused by Apple gcc and flex bugs, including
  hanging on an end-of-file inside a comment
* code cleaning to remove unused code and avoid many compiler warnings

Overview of Changes in Maude alpha100 (source trees 97, 98, 99 abandoned)
=========================================================================
* added crude Maude VM based interpreter (sreduce)

Overview of Changes in Maude alpha96c
=====================================
* added unification support for CU, U, Ul and Ur theories
* fixed two related bugs where unifying a variable against a variable
  generating an implicit renaming caused an in-theory occurs check issue
  leading to non-termination
* fixed a bug in the AC/ACU unification code where binding a variable to an alien
  subterm caused a variety effects including missing unifiers and nontermination
* performance fixes for AC/ACU unification where subterms cancel
* fixed a GC bug in AC/ACU unification
* fixed a bug where printing the empty QID in loop mode caused an out-of-bounds
  memory read
* fixed a bug in the free theory semi-compilation of variant equation left hand sides

Overview of Changes in Maude alpha96b
=====================================
* fixed bug in variant narrowing of ground terms
* fixed memory corruption bug in sockets
* the print attribute now flushes its output
* fixed a long standing bug where sockets could appear to be dropped on Mac

Overview of Changes in Maude alpha96a
=====================================
* hack to allow building 64-bit binaries under Darwin
* fixed bug in metaGenerateVariant() with singleton substitutions
* fixed variable name clash bug in narrowing
* support for irreducibility constraints in variant narrowing
* support for variant unification

Overview of Changes in Maude alpha96
====================================
* fixed bug in narrowing where unifiers were being eagerly rewritten in place
* fixed bug in narrowing caused by abstraction variables
* fixed bug in pretty printing of equation attributes
* fixed fresh variable clash bug in narrowing
* first attempt at supporting variant narrowing

Overview of Changes in Maude alpha95c
=====================================
* fixed a bug where stale information about fresh variables was not
  being cleaned up when backing out of a unification branch that
  generated those variables
* a bug where the socket write code was using memory might have been
  deallocated
* patched around apparent weirdness in rope::c_str()

Overview of Changes in Maude 2.6 (alpha95b)
===========================================
* fixed a bug in the profiler provoked by condition fragments in a
command or descent function invocation
* more overparsing
* avoid unnecessary right id sort checking for commutative symbols

Overview of Changes in Maude alpha95a
=====================================
* fixed sort bug with new memo mechanism
* added MAUDE_META_MODULE_CACHE_SIZE environment variable

Overview of Changes in Maude alpha95
====================================
* fixed bug where tokens starting in . that followed a . that might
have, but didn't terminate a statement or command were having their
initial . split off
* handle collapse down cases in order sorted unification
* hash consing used for srewrite
* fixed a bug in the ACU matcher where bad solutions could be
generated by the lazy red-black algorithm for certain nonlinear
patterns
* fixed a bug in the module system where errors in modules constructed
for module expressions could cause a crash
* memo attribute reimplemented using hash consing
* a memory corruption bug in the compilation of variant equations whose
left hand side is headed by a free function symbol

Overview of Changes in Maude alpha94a
=====================================
* fixed bug where downTerm() could return terms in the wrong kind
* changed handling of operator names that are a single special
  character
* implemented compound cycle breaking for unification
* optimizations for ACU unification
* changed handling of variable bindings for unification

Overview of Changes in Maude alpha94
====================================
* fixed bug where hash consing wasn't being used for model checking
  after all.
* fixed bug where empty sort declaration crashed show module command
* fixed bug where op->op mapping in a theory-view could be ignored if
  followed by an op->term mapping in another view
* fixed bug in upView() where op->term mappings were not being lifted
  to the metalevel correctly.
* fixed potential bug in garbage collection of dags produced by
unification if rewriting takes place between the generation of two
unifiers
* partial implementation of ACU unification.

Overview of Changes in Maude 2.5 (alpha93d2)
============================================
* BOOL-OPS split off BOOL in prelude

Overview of Changes in Maude alpha93d
=====================================
* fixed bug where fail term attachments to polymorphs cause crash
* fixed bug where flattened meta-modules produced by upModule() still
  had parameters

Overview of Changes in Maude alpha93c
=====================================
* fixed bug where upView was producing bad metaViews

Overview of Changes in Maude alpha93b
=====================================
* fixed bug in handing of metaRenamings

Overview of Changes in Maude alpha93a
=====================================
* changed AC constraint propagation algorithm to reduce the risk of
  exponential blow up at semi-compile time
* changed free theory constraint propagation algorithm to reduce the
  risk of exponential blow up at semi-compile time

Overview of Changes in Maude alpha93
====================================
* fixed performance bug with huge AC/ACU right hand sides
* fixed symmetric performace bug in A/AU theory
* fixed a A/AU rewriting with extension bug
* graceful recovery from tabs in string literals
* optimizations for construction of rhs instances
* bug where single token op names containing a string part were
  considered to have mixfix syntax
* unification code cleanup and potential bug fixed

Overview of Changes in Maude alpha92c
=====================================
* fixed metaPrettyPrint() bug in assoc, with paren case
* tail recusion elimination for dag node comparison
* various low level optimizations

Overview of Changes in Maude alpha92b
=====================================
* fixed failure to GC in rules only search
* fixed unstackable flag bug in CUI theory
* first attempt at hash consing for search/model checking
* unrewritable/unstackable optimization for search/model checking

Overview of Changes in Maude alpha92a
=====================================
* fixed BDD variable bug introduced by lazy computation of symbol sort
  calculation BDDs in alpha92
* fixed bug where free, fresh variables were not constrained to have a
  valid sort
* partly fixed a performance bug in constraint propagaion analysis
  phase of pattern compilation
* partial support for strat in metalevel builtins

Overview of Changes in Maude alpha92
====================================
* fixed a bug in unification sort calculations on polymorphic symbols
* if_then_else_fi now uses generic sort mechanism and can give
  preregularity warnings
* fixed module reparsing bug
* fixed CUI matcher bug
* fixed pending unification stack bug
* added rewrite condition fragments to search command
* fixed instantiation by theory-view bug
* added meta-view syntax and upView() operator
* first attempt at meta-interpreter

Overview of Changes in Maude 2.4 (alpha91d)
===========================================
* fixed AU term normalization bug

Overview of Changes in Maude alpha91c
=====================================
* Special case optimization for AC/ACU matching with extension

Overview of Changes in Maude alpha91b
=====================================
* Removed extranous debugging print statement

Overview of Changes in Maude alpha91a
=====================================
* Now solve diophantine equations over ints rather than mpzs for
  unification
* Extended unify command to handle systems
* Added print attribute
* Fixed Diophantine solver bug for results over 2^31 - 1
* Install .maude files in the data directory
* Fixed free theory discrimination net subsumption bug
* Fixed gcc4 incompatibilities
* Outlawed overloading operations from a parameter theory
* Fixed longstanding stdout/stderr synchonization bugs

Overview of Changes in Maude alpha91
====================================
* fixed bug where natSystemSolve() would lose hooks during importation
* fixed bug where unify command was not cleaning up after bad
  unification problem

Overview of Changes in Maude alpha90a
=====================================
* added stack overflow handling using libsigsegv
* semi-compilation of right hand sides optimized for huge right hand
  sides 
* construnction of free theory discrimination nets optimized for large
  numbers of equations

Overview of Changes in Maude alpha90
====================================
* new unification combination scheme to avoid AC cycling bug
* C unification is smarter about avoiding redundant unifiers
* reorganized surface syntax parser to allow deeply nested terms
* more overparsing 

Overview of Changes in Maude alpha89j (not released)
====================================================
* fixed bug that cause solved form subproblems to be lost in
  commutative unification
* added single redex per state narrowing option

Overview of Changes in Maude alpha89i
=====================================
* fixed two bugs which caused narrowing structures not to be deleted
* allow multiple calls to cached desent functions with same arguments
  to be efficient in most cases
* added another narrowing descent function

Overview of Changes in Maude alpha89h
=====================================
* crude support for narrowing
* fixed bug with condition fragment collapses during processing
* fixed memory leak in AU term collapses

Overview of Changes in Maude alpha89g
=====================================
* fixed selection from basis bug in AC unification algorithm
* allow unification to work on ground terms from unimplemented
  theories; made recovery in unimplemented cases consistent

Overview of Changes in Maude alpha89f
=====================================
* fixed bug where large AC dags could get normalized into tree form
  during unification with resulting chaos
* fixed C unification breakage from alpha89c

Overview of Changes in Maude alpha89e
=====================================
* fixed bug where we were deleting unification subproblems twice
* fixed module name in "no module" warning

Overview of Changes in Maude alpha89d
=====================================
* fixed bug where we were not reserving enough BDD variables for free
  variable sorts

Overview of Changes in Maude alpha89c
=====================================
* fixed bug iter theory matching with extension could return a match
  where the matched portion was alien
* added unification with extension
* reimplement meta-unification interface to support control over fresh
  variable names and disjoint unification
* allow spaces in file names using \ and "" conventions

Overview of Changes in Maude alpha89b
=====================================
* fixed bug where early unification failure caused memory corruption

Overview of Changes in Maude alpha89a
=====================================
* fixed bug where syntax could leave renaming in bad state
* fixed bug where were were passing variable->BDD mappings by value
rather than by reference
* fixed bug where we weren't clear new substitutions in CUI
unification
* fixed bug where we weren't deleting subproblems in unification
problems

Overview of Changes in Maude alpha89
====================================
* fixed bug where new unsorted unifier would not be look for after an
  unsorted unifier failed to have at least one sorted solution
* fixed bug where non-unifiers were generated in deeply nested
  commutative unification examples
* fixed bug where command line files were ignored with -no-prelude
  flag
* use dag solved forms for unification
* first support for AC unification

Overview of Changes in Maude 2.3 (alpha88f)
===========================================
* added commutative unification
* fixed free theory instantiation bug
* fixed sort calculation of S_Theory terms bug
* fixed unification with too many variables bug
* added iter theory unification

Overview of Changes in alpha88e
===============================
* string, qid and float constants allowed in unification
* fixed unify f(X, Y) =? f(Y, X)  bug

Overview of Changes in Maude alpha88d
=====================================
* set trace builtin on/off command
* state caching in strategy language
* first suppport for unification

Overview of Changes in Maude alpha88c
=====================================
* extra advisories in metalevel
* min/max operators in FLOAT
* slight change to search semantics
* metalevel projection functions now support parameterized metamodules
* fixed kind printing bug in metaPrettyPrint()
* erwrite supports limit and continue

Overview of Changes in Maude alpha88b
=====================================
* minor syntactic changes to appease gcc 4.1
* minor importation changes in prelude.maude and model-checker.maude
* fixed extension tracing bugs in search/model checker, strategy
  language and metalevel
* revised/extended strategy language; cont now works with srew
* fixed trace condition bug

Overview of Changes in Maude alpha88a
=====================================
* many changes to the prelude to fix unsoundness concerns
* process based reimplementation of strategy language
* better overparsing for operator declarations
* fixed bug with views mapping to terms from FLOAT/STRING/QID
* fixed bug in AU unique collapse matcher
* fixed bug that allowed parsing of parameterized theories
* fixed upModule() bug affecting renamings
* fixed metaXmatch() kind bug introduced by alpha86 fix
* subset tests for SET and SET*
* predefined term ordering module

Overview of Changes in Maude alpha88
====================================
* fixed more sufficient completeness issues
* search command now takes a depth bound
* added metaNormalize()
* added machine ints module

Overview of Changes in Maude alpha87a
=====================================
* fixed bug in ! strategy combinator
* fixed long standing bug in look up code for assoc ops

Overview of Changes in Maude alpha87
====================================
* crude first version of strategy language

Overview of Changes in Maude 2.2 (alpha86e)
===========================================
* fixed long standing metalevel prec bug

Overview of Changes in Maude alpha86d2
======================================
* reorganized metalevel list sorts to fix sufficient completeness
  problem 

Overview of Changes in Maude alpha86d
=====================================
* fixed stale pointer bug in view reevaluation
* minor fixes to prelude.maude
* fixed uninitialized format attribute bug
* fixed parameter theory module expression memory leak
* fixed polymorph identity memory leak
* fixed polymorph identity processing bug
* added and used QID-SET fmod
* fixed metamodule cache deletion bug
* sortLeq and lesserSort now work on types

Overview of Changes in Maude alpha86c
=====================================
* improved recovery from surface syntax errors
* added DEFAULT fth, various views and ARRAY fmod
* added LIST-AND-SET fmod
* added linear Diophantine solver
* warn about object level duplicate attributes
* fixed backquote in created module name bug
* fixed view ACU op->term mapping bug
* added -no-wrap command line option
* disallow parameter passing in nonfinal instantiations
* allow renaming of modules with bound parameters

Overview of Changes in Maude alpha86b
=====================================
* module garbage collection bug fixed
* metasummation bug fixed
* target modules with free parameters no longer allowed in views
* illegal importations no longer tolerated
* views can no longer map module defined stuff
* renamings can no longer map parameter defined stuff
* operator mappings now allowed in views
* dependency tracking supports views
* meta support for parameterization
* identity elements added for various structures in prelude

Overview of Changes in Maude alpha86a
=====================================
* fixed parameter checking bug for modules with both free and bound
  parameters
* structured sorts printed correctly in various places
* theory-views now pushed into parameterized sorts
* new naming convention for otf modules
* bound parameter instantiation now handled like Full Maude
* -no-advise command line flag
* declined messages to external objects generate advisories

Overview of Changes in Maude alpha86
====================================
* fixed loop mode \/ bug
* metaPrettyPrint() now supports options
* preregularity and constructor consistancy errors now produce a
  single informative warning
* set trace rewrite and set trace body options
* fixed metaXmatch() kind clash bug
* SO_REUSEADDR flag set on server sockets
* first attempt at parameterization in module system

Overview of Changes in Maude alpha85a
=====================================
* fixed more sufficient completeness issues in the prelude
* metadata attribute now allowed for operator declarations
* added crude support for sockets as external objects

Overview of Changes in Maude alpha85
====================================
* added min/max functions to number hierarchy
* fixed bug in up'ing FloatOpSymbol hook
* fixed sufficient completeness issues in the prelude
* fixed a bug in up'ing terms which gave kind variables the wrong
  sort
* glbSorts() now handles kinds
* show profile now includes percentages
* show path labels command added
* metaSearchPath() added
* set clear rules on/off command added
* maximalAritySet() added

Overview of Changes in Maude alpha84d
=====================================
* fixed 0.0 ^ -1.0 bug
* module selectors now support theories

Overview of Changes in Maude alpha84c
=====================================
* added random number generation
* added counters
* trace applications in metaApply()/metaXapply()

Overview of Changes in Maude 2.1.1 (alpha84b.2)
===============================================
* fixed op renaming bug

Overview of Changes in Maude alpha84b.1
=======================================
* fixed AU sort calculation bug

Overview of Changes in Maude alpha84b
=====================================
* set protect/extend <module> on/off added, BOOL now protected
* fixed upModule() bug wrt CUI_NumberSymbol and ACU_NumberSymbol hooks
* theory syntax and meta-syntax added
* fixed label renaming bug
* overparsing added
* warnings added for illegal ad hoc overloading
* rudimentary checking for bubble hooks
* fixed missing id importation bug

Overview of Changes in Maude 2.1 (alpha84)
==========================================
* added -no-banner flag
* fixed bug where syntax errors corrupted memory
* added rudimentary test suite

Overview of Changes in Maude alpha83a
=====================================
* fixed crash that occurred when bubbles are imported
* fixed memory corruption when copying persistent representations
* fixed crash on imported module overwrite following a descent
  function failure
* simple module expressions are now supported at both the object and
  metalevel 
* bashing together unrelated sorts and ops is now legal
* added show modules command

Overview of Changes in Maude alpha83
====================================
* made polymorphs explicit with poly attribute
* added many new metalevel functions
* fixed meta-context iter bug
* fixed object level Bubble-Exclude bug
* show all/show module now prints specials

Overview of Changes in Maude alpha82
====================================
* fixed crash that occurred when printing redeclaration of sort error
  from the metalevel
* extended quo/rem/gcd/lcm/divides to Rats
* made constructor coloring work corectly for iter operators
* changed operational semantics of owise equations wrt nondefault
  operator stategies
* fixed bugs in show module/show all commands
* fixed metaPrettyPrint kind variable bug
* fixed break point with builtin op seg fault
* added upTerm() and downTerm()
* Infinity/-Infinity now work on FreeBSD & MacOSX
* building with Tecla is now optional

Overview of Changes in Maude 2.0.1 (alpha81)
============================================
* switched build system to autoconf/automake
* many portability fixes
* added --help and --version flags
* fixed infinite recursion with unary empty syntax bug
* internal ordering on Qids is now alphabetical
* fixed serious bugs in the ACU matcher