OpenFst: Release 1.6
      * The `first_path` option to ShortestPath is now optimal for A* (1.6.7)
      * Renames SymbolTable::kNoSymbol to kNoSymbol (1.6.7)
      * Exposes PowerMapper to the scripting API (1.6.7)
      * Fixes linking of the special SOs (1.6.7)
      * Fixes error handling in HashMatcher (1.6.6)
      * Adds kShortestDelta for operations dependent on shortest-distance (1.6.6)
      * Adds Python methods for (un)pickling and (de)serializing FSTs (1.6.6)
      * Adds constructive variants of Invert and Project (1.6.6)
      * Increases code sharing in MemoryPool/MemoryArena (1.6.6)
      * Improves consistency of matcher FST ownership (1.6.6)
      * Adds non-trivial A* estimator class (1.6.6)
      * Prevents unreachable code generation in libfstscript (1.6.5)
      * Adds move constructors for non-trivial weight types (1.6.5)
      * Standardizes method names for tuple weight types (1.6.5)
      * Eliminates undefined behavior in weight hashing (1.6.5)
      * Optimizes binary search in SortedMatcher (1.6.5)
      * Adds SetWeight (1.6.5)
      * Fixes typing error in Python FAR reader (1.6.4)
      * Removes restriction that Prune argument have commutative weights (1.6.3)
      * Improves configuration of CompositeWeight readers and writers (1.6.3)
      * Improves accuracy of ShortestDistance summation (1.6.3)
      * SetFinal now "moves" its weight argument (1.6.3)
      * Exposes ArcIterator and EncodeMapper flags in Python (1.6.3)
      * Properly sets return codes in FST binaries (1.6.3)
      * Eliminates StringWeight macros (1.6.3)
      * Finalizes most virtual method overrides (1.6.2)
      * Fixes missing includes of <fst/log.h> (1.6.1)
      * Adds float format support to FST drawing (1.6.1)
      * Extensive modernization for C++11 style (1.6.0)
      * Many classes and constants moved into an internal namespace (1.6.0)
      * Adds HashMatcher (1.6.0)
      * Adds Member method to SymbolTable (1.6.0)
      * Adds the "special" extension and the fstspecial binary; this is similar to
        fstconvert but accepts arguments for specifying special labels (phi, rho,
        and sigma) of FSTs (1.6.0)
      * Exposes allow_negative_label option for Python symbol tables (1.6.0)
  
  OpenFst: Release 1.5
      * Added p-subsequential determinization (1.5.0)
      * Generalized epsilon normalization to non-functional case (1.5.0)
      * Added general gallic (plus is union) semiring (1.5.0)
      * Added FST compression extension (1.5.0)
      * Added Python extension (1.5.0)
      * Added multiple pushdown transducer (MPDT) support (1.5.0)
      * Fixed Isomorphic function (1.5.0)
      * Added final method to matchers (1.5.0)
      * Fixed various compiler issues (1.5.0)
      * Fixed missing Isomorphic components (1.5.0)
      * Added UnionWeight (1.5.0)
      * Added InputEpsilonMapper and OutputEpsilonMapper arc mappers (1.5.1)
      * Added TrivialComposeFilter for more efficient composition when one
        of the arguments is epsilon-free (1.5.1)
      * Added properties bits kUnweightedCycles and kWeightedCycles (1.5.1)
      * Added missing const qualification to (1.5.1):
        - SymbolTableIterator access
        - EncodeMapper writing to file
        - EncodeMapper SymbolTable access
      * Replaced internal custom reference-counting (RefCounter) with
        C++11 smart pointers where possible, and fixed associated
        reference-counting bugs (1.5.1)
      * When calling DeleteStates on a MutableFst with a shared impl, the impl
        is set to a new empty impl rather than copying and deleting (1.5.1)
      * Prepended `Pdt` to the Expand libraries and classes in the PDT
        extension, and prepended `MPdt` to the Expand libraries and classes
        in the MPDT extension, so that both can be used in the same compilation
        unit (1.5.1)
      * Added option to PDT Replace for compiling a strongly-regular RTN into a
        bounded-stack PDT (1.5.1)
      * Improved symbol table support for PDT Replace, including automatic
        generation of parentheses symbols (1.5.1)
      * Improvements to scripting API (1.5.1):
        - Added methods for FST access and mutation
        - Added additional checks for arc/weight compatibility
        - WeightClass::One and WeightClass::Zero now require a specified weight
          type at time of construction
        - Improved VectorFstClass constructors
        - Added linear-time check for cyclic dependencies in Replace
        - Added EncodeMapperClass, a template-free box for an EncodeMapper
      * Improvements to the binaries (1.5.1):
        - Fixed no-op --precision flag to fstdraw (1.5.1)
        - Fixed no-op --file_list_input flag to farcreate (1.5.1)
      * Improvements to the Python extension (1.5.1):
        - Added methods for creating an empty mutable FST
        - Added methods for FST access via state and arc iteration
        - Added FST compilation from arclists (cf. fstcompile)
        - Added FST printing and drawing
        - Added FarReader and FarWriter classes.
      * FarReader's GetFst method now returns a pointer (1.5.2)
      * Fixed FSTERROR macro (1.5.2)
      * Fixed build flags for dlopen (1.5.2)
      * Consolidated Python extension into single module (1.5.2)
      * Python add_arc now takes an Arc object (1.5.2)
      * Adds optional minimization of non-deterministic FSTs (1.5.3)
      * Mutation methods of the Python Fst object now support chaining (1.5.3)
      * Scripting API and Python weight objects now support semiring arithmetic
        (1.5.3)
      * Adds RemoveSymbol method to SymbolTable (1.5.4)
      * Prevents underflow when using LogProbArcSelector in random generation
        (1.5.4)
      * Makes random weight generators a single template class (1.5.4)
      * Makes weight Properties constexpr where possible (1.5.4)
      * Adds check for error when opening files when compiling strings into FARs
        (1.5.4)
      * Adds routines for parsing string flags to the scripting API (1.5.4)
  
  OpenFst: Release 1.4
      * Port to C++11 (1.4.0)
      * Disambiguate function added (1.4.0)
      * Isomorphic function added (1.4.0)
      * Matcher interface augmented with Priority method.
      * Special matchers (rho/sigma/phi) can match special symbols
        on both input FSTs in composition/intersection provided at each
        state pair they only match one side (1.4.0)
      * Added ExplicitMatcher to suppress implicit matches (e.g. epsilon
        self-loops) (1.4.0)
      * Linear{Tagger,Classifier}Fst extensions added (1.4.0).
      * Generalized state-reachable to work when input is cyclic (so long as no
        final state is in a cycle). This ensures label-reachable (and hence label
        lookahead) works with cyclic input (1.4.0)
      * Added Condense to build the condensation graph (SCCs condensed to single
        states) of an FST (1.4.0).
      * Added an option to Reverse to specify whether a super-initial state
        should always be created (1.4.0).
      * Fixed bugs in FirstCacheStore, PowerWeight, and StringCompiler (1.4.0).
      * Changed SymbolTable to use faster data structure (1.4.0).
      * Added 'min' disambiguation in determinizaton to keep only the minimum
        output in a non-functional transducer when plus=min/max
        (flag --disambiguate_output) (1.4.1)
      * Compiler issues in linear-fst fixed (1.4.1)
  
  OpenFst: Release 1.3
      * Support for non-fatal exits on errors: (1.3.1)
        - Added FLAGS_fst_error_fatal: FST errors are
          fatal if true (default); o.w. return objects flagged as bad:
          e.g., FSTs - kError
          prop. true, FST weights - not a Member().
        - Added kError property bit signifying bad FST
        - Added  NoWeight() method to FST weight requirements that returns
          weight that is not a Member().
      * Various improvements to the FAR extensions (1.3.1)
        - a single FST is now a FAR type
        - FLAGS_initial_symbols: Uses the symbol table from the
          first FST in the archive for all entries"
        - Input/output to standard input/output for some FAR and arc types
      * --with-icu configuration option no longer needed (1.3.1)
      * Improved flags usage esp. if use SET_FLAGS not SetFlags/InitFst (1.3.2)
      * Added 'fst' as possible far writer type (1.3.2)
      * phi matcher can now accept 0 as the phi label (1.3.2)
      * Added ngram-fst extension (1.3.2)
      * Improved performance of PDT composition (1.3.3)
      * Memory-map support (1.3.3)
      * Fixed cross-FST serialization issues (1.3.3)
      * Fixed NGramFst off-by-one issue (1.3.3)
      * farextract now allows one to specify a list of comma-separated keys,
        including key ranges (1.3.3)
      * Fixed bug in PDT replace that could cause close paren IDs to collide
        with open paren IDs (1.3.4)
  
  OpenFst: Release 1.2
      * Added lookahead matching and filtering for faster composition
      * Added EditFst for mutation of o.w. immutable FSTs
      * Added script sub-namespace defining type FstClass, a non-templated
        Fst<Arc> to hold the arc template type internally. This and FST
        operations on it allow easier I/O and scripting at the cost of some
        runtime dispatching.
      * Added per-arc-iterator control of Fst caching.
      * Added PowerWeight and Power Arc.
      * Added SparsePowerWeight and SparsePowerArc (1.2.4)
      * Added SignedLogWeight and SignedLogArc (1.2.4)
      * Added ExpectationWeight and ExpectationArc (1.2.4)
      * Added AStarQueue, PruneQueue and NaturalPruneQueue disciplines (1.2.6)
      * Added Log64Weight and Log64Arc to FST library throughout, including 
        support throughout scripts/bins/dsos (1.2.8)
      * Added delayed RandGenFst that outputs tree of paths weighted
        by count (1.2.8)
      * Added fstsymbols shell-level command
      * Added total weight removal option to pushing
      * Changed methods for symbol table mutation:
        use MutableInputSymbols()/MutableOutputSymbols().
      * Numerous efficiency improvements esp in composition, replace, and caching
      * Made "fstmap" handle semiring conversion by adding "to_std", "to_log"
        and "to_log64" as supported 'map_type' arguments (1.2.8).
      * Made the destructive implementation of RmEpsilon skip over states
        admitting no non-epsilon incoming transition (1.2.8).
      * Fixed numerous bugs (1.2 through 1.2.9) including:
        - improper types of some approximation deltas
        - sub-optimal hashing functions
        - issues in internal reuse of shortest distance
        - hashing bug in FloatWeight
        - bug in shortest path queue
        - symbol table checksumming issues
        - various C++ standards issues
        - Visit() behavior when visitation aborted
        - Decode() hash performance bug (1.2.1)
        - EditFst::Copy(bool) method when the boolean parameter is true (1.2.7)
        - SymbolTable memory leak in Invert() (1.2.8)
        - Added escaping of " and \ in labels in fstdraw, needed for dot to
          function properly (1.2.8)
        - Fixed handling of final weight of start state in fstpush (1.2.8)
        - Added FST_LL_FORMAT to fix 64-bit integer printf issues (1.2.9)
        - Fixed missing <functional> includes (1.2.9)
        - Fixed reused local variable names (1.2.9)
        - Fixed passing string by reference in FstDraw args (1.2.9)
      * Added extensions directories including:
        - finite-state archive (FAR) utilities,
          added stlist format supporting writing/reading to/from standard out/in
          at the library-level (1.2.8)
        - compact fsts
        - lookahead fsts
        - pushdown transducers (improved in 1.2.1 through 1.2.7).
      * Added StateMap/StateMapFst; renamed Map/MapFst to ArcMap/ArcMapFst;
        map/MapFst retained (but deprecated) (1.2.9)
      * Deleted ArcSum() and ArcMerge; use StateMap w/ ArcSumMapper and
        ArcUniqueMapper (1.2.9).
      * Incremented version of ConstFst/CompactFsts to stop memory alignment
        that fails on pipes. Made old version raises errors when read on
        pipes (1.2.9).
      * Improved determinize hash (1.2.9)
      * Removed stdio uses (1.2.10)
      * Fixed library ordering issues esp. with newer GNU build tools (1.2.10)
  
  OpenFst: Release 1.1
      * Added compat.h to src/include/fst to fix missing defines
      * Fixed bug in acyclic minimization that led to non-minimal
        (but equivalent) results
      * Fixed missing FST typedef in various matchers in matcher.h
        so that they can be cascaded
      * Opened file streams binary where appropriate
  
  OpenFst: Release 1.0 (Additions to beta version):
      * Matcher class added for matching labels at FST states. Includes
        special matchers for sigma (any), rho ('rest'), and phi ('fail')
        labels.
      * Composition generalized with arbitrary filters, matchers, and state
        tables.
      * Sequence and matching composition filters provided. (see compose.h,
        compose-filter.h, matcher.h, state-table.h)
      * Unique n-best (see shortest-path.h)
      * Pruning in determinization and epsilon removal (see determinize.h,
        rmepsilon.h)
      * New Fst class:
         * Compact Fsts for space-efficient representation (see compact-fst.h)
      * New Weight classes:
         * MinMax
         * Lexicographic
      * Miscellaneous bug fixes