# Changelog

## Version 1.3 — 2025-08-14
### Added
* decision procedures for SPL (strictly piecewise-local)
* join-semigroups and join-monoids
  + syntacticJSemigroup and syntacticSemilattice to compute them
  + a new Porter, LTK.Porters.SyntacticSemilattice to display them
  + isJoinVariety and isMJoinVariety for arbitrary membership queries
  + :isJVarietyS and :isJVarietyM in plebby
  + :isJVarietyT is the natural extension to tiers of :isJVarietyS
* LTK.FSA.renameSymbolsByMonotonic is now exported
* classify synonyms to match plebby but retain compatibility:
  + "1" is now also "Trivial" from :isTrivial
  + "Fin" is now also "Finite" from :isFinite
* classify now accepts "Dot1" and "SPL"
### Changed
* improved some documentation inside plebby
* fixed one of the examples
* LTK.Porters.Pleb was redesigned in terms of recursive schemes
* moved optimization level from language-toolkit.cabal to cabal.project
### Removed
* The Ord instance for FSA was a dangerous lie, it is now gone.


## Version 1.2.0.1 — 2024-04-27
### Changed
* PLEB: fixed @@ ("Domination") operator
* reenabled -O2 compilation

## Version 1.2 — 2024-04-16
### Added
* commonPrefix and commonSuffix functions on automata
* isDot1 (dot depth at most one)
* syntacticSemigroup (interfacing with finite-semigroups)
* syntacticOMonoid, syntacticOSemigroup (ordered monoid or semigroup)
* isVarietyS (ordered varities from finite-semigroups)
* plebby:
  + new, more detailed :help system
  + strict order (`.∙.(x,y)` asserts start of `x` precedes start of `y`)
  + Ctrl+C interrupts handled, abort current computation
### Changed
* algebraic tools split and expanded in a new package (finite-semigroups)
* plebby:
  + inequalities supported in :isVarietyM/S/T for order
  + better error messages
  + bugfix: two-expression commands no longer break on "it"
* many classification tasks now use semigroups from finite-semigroups
* bugfix: trimUnreachables handles epsilon-edges and avoids recomputation

## Version 1.1 — 2023-06-18
### Added
* preliminary French translation of manual pages
* basic Emacs mode for syntax highlighting
* classification procedures
  + isAcom (aperiodic and commutative)
  + isLAcom (locally isAcom)
  + isFO2BF (two-variable FO with betweenness of factors)
  + isVariety (Plebby has one command each for *, +, and tier)
  + isMTF, isMTDef, isMTRDef, isMTGD (simple multitier classes)
* Porters
  + egg-box diagrams
  + graphs of syntactic orders
* Pleb syntax
  + empty variadics
  + reversal (`⇄`)
  + upward closures (`↑`, or `loopify` in the library)
  + shuffle products (`⧢` or `autShuffle` in the library)
  + symbol neutralization (`|syms|`, or `neutralize` in the library)
  + nonempty iteration (`+e` equivalent to `@(e,*e)`)
* Plebby commands
  + `:cequal` and `:cimplies` to account for the semantics
  + `:eggbox` (display the egg-box)
  + `:synord` (display syntactic order)
* Plebby configuration file
### Changed
* bugfix: omega function works in properly regular semigroups
* performance enhancement: faster FO2(S) test
* performance enhancement: faster (co)finite test
* performance enhancement: faster SP test

## Version 1.0.1 — 2022-03-28
### Changed
* fixed a mistest in `classify`, as well as a severe performance issue

## Version 1.0 (initial hackage release) — 2022-03-15
### Added
* `classify` command
* LTK.Algebra module and new decision procedures `LTK.Decide.*`
  + B
  + CB
  + Definite, (T)(R)Def restrictions on suffixes or prefixes (on tiers)
  + Finite
  + FO2, FO2S, FO2B: definable in two-variable FO with <, (<,+1), (<,bet)
  + GD: generalized definite, prefixes AND suffixes
  + GLPT: generalization of LPT
  + GLT: generalization of LT
  + LPT: locally J-trivial, contains combinations of piecewise-local factors
  + TLPT: tier-based LPT
  + Trivial: accepts ALL strings, or NO strings
  + associated `:isCLASS` plebby commands
* LTK.DecideM: classify monoids, to avoid recomputation
* left- and right-quotients in `LTK.FSA` and in PLEB
* union and intersection of symbol sets wherever they may appear in PLEB
* downward closure in PLEB
* `:Jmin` plebby command for displaying a graph of J-classes
### Changed
* **`dotify` now uses AT&T format instead of Jeff format**
* **`factorize` now uses AT&T format instead of Jeff format**
* improved AT&T import and export
### Removed
* stress-specific symbols in `LTK.Factors`

## Version 0.3 — 2020-09-16
### Added
* AT&T import and export `LTK.Porters.ATT`
* prefix-tree import from corpus `LTK.Porters.Corpus`
* string-extension learners `LTK.Learn.*`
* more `plebby` commands
  + AT&T import and export `:readATT`, `:readATTO`, `:writeATT`
  + learners `:learnSL`, `:learnSP`, `:learnTSL`
### Changed
* extraction is now a submodule: `LTK.Extract.SL` not `LTK.ExtractSL`, etc

## Version 0.2 — 2019-09-01
### Added
* more decision algorithms `LTK.Decide.*`
  + LT: locally testable, defined by sets of k-substrings
  + LTT: locally threshold-testable, FO[+1]
  + PT: piecewise-testable, defined by sets of k-subsequences
  + SF: star-free, aperiodic, star-height zero
  + SL: the decider formerly in `LTK.ExtractSL`
  + SP: the decider formerly in `LTK.ExtractSP`
  + TLT: tier-based LT
  + TLTT: tier-based LTT
  + TSL: tier-based strictly local
### Changed
* factor extraction is now `LTK.Extract.*`

## Version 0.1 — 2019-08-23
* moved to a Cabal-based installation format
* removed several exploratory files
* add computations over tiers

## Version 0.01a — 2018-12-20
* initial full public release