# agum

Unification and Matching in an Abelian Group

 Latest on Hackage: 2.7

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GPL licensed
Maintained by
This package contains a library for unification and matching in
an Abelian group and a program that exercises the library.

\$ agum
Abelian group unification and matching -- :? for help
agum> 2x+y=3z
Problem: 2x + y = 3z
Unifier: [x : g0,y : -2g0 + 3g2,z : g2]
Matcher: [x : g0,y : -2g0 + 3z]

agum> 2x=x+y
Problem: 2x = x + y
Unifier: [x : g1,y : g1]
Matcher: no solution

agum> 64x-41y=a
Problem: 64x - 41y = a
Unifier: [a : 64g1 - 41g2,x : g1,y : g2]
Matcher: [x : -16a - 41g6,y : -25a - 64g6]

agum> :quit

## Changes

2018-01-06 John D. Ramsdell <ramsdell@mitre.org>

* src/Algebra/AbelianGroup/Main.hs (readM): Adapted the code to
work when Monad no longer has a fail method.

2015-04-27 John D. Ramsdell <ramsdell@mitre.org>

* src/Algebra/AbelianGroup/Main.hs (AnsErr): Added Functor and
Applicative instance so that the code compiles in GHC 7.10.
Thanks go to Douglas McClean.

* agum.cabal (Version): Released as version 2.6

2013-02-21 John D. Ramsdell <ramsdell@mitre.org>

* agum.cabal (Location): Added repository location.

* agum.cabal (Version): Released as version 2.5

2012-02-29 John D. Ramsdell <ramsdell@mitre.org>

* agum.cabal (Version): Released as version 2.4. Also,
constrained the containers package to be 0.3 or greater.

* src/Algebra/AbelianGroup/UnificationMatching.hs: Replaced
occurrences of Data.Map.foldWithKey by Data.Map.foldrWithKey as
the former has been deprecated.

2010-06-21 John D. Ramsdell <ramsdell@mitre.org>

* agum.cabal (Version): Released as version 2.3.

* agum.cabal (Build-Depends): changes dependency to
base >= 3 && <5, containers

2009-09-17 John D. Ramsdell <ramsdell@mitre.org>

* agum.cabal (Version): Released as version 2.2.

2009-09-14 John D. Ramsdell <ramsdell@.mitre.org>

* src/Algebra/AbelianGroup/IntLinEq.hs: Integer solutions to
linear equation solver was placed in its own module.

2009-09-13 John D. Ramsdell <ramsdell@mitre.org>

* src/Algebra/AbelianGroup/UnificationMatching.hs (unify): Changed
the result to be a substitution since unification always succeeds.

2009-09-05 John D. Ramsdell <ramsdell@mitre.org>

* src/Algebra/AbelianGroup/UnificationMatching.hs: Added
reference to Andrew Kennedy's Ph.D. thesis as it contains a proof
of correctness of the implemented matching algorithm.

* agum.cabal (Version): Released as version 2.1.

2009-08-29 John D. Ramsdell <ramsdell@mitre.org>

* src/Algebra/AbelianGroup/UnificationMatching.hs (Substitution,
apply): Hid the representation of a substitution and supplied a
function for applying a substitution to a term.

* agum.cabal (Version): Released as version 2.0.
Depends on 2 packages:
Used by 1 package:
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