at.jku.risc.stout.nau.algo

Class EquivarianceSystem

java.lang.Object

at.jku.risc.stout.nau.algo.EquivarianceSystem

public class EquivarianceSystem
extends Object

This class represents a rule based system to compute an equivariance permutation for nominal terms by atom swapping. The nominal terms will be alpha equivalent under the computed permutation. This algorithm is used as auxiliary task in AntiUnifySystem.
The algorithm E is described in the paper:
Alexander Baumgartner, Temur Kutsia, Jordi Levy and Mateu Villaret, Nominal Anti-Unificaion

Author:

Alexander Baumgartner

Constructor Summary

Constructors

Constructor and Description
EquivarianceSystem(NodeFactory factory)
EquivarianceSystem(NodeFactory factory, EquationSystem<EquivarianceProblem> problemSet)

Method Summary

Methods

Modifier and Type	Method and Description
void	addEquation(NominalTerm eq1Left, NominalTerm eq2Left, boolean deepCopy) Adds a matching problem to the problem set.
EquivarianceSystem	clear()
Permutation	compute() Computes the equivariance permutation silently.
Permutation	compute(DebugLevel debugLevel, PrintStream out) Computes an equivariance permutation for given equivariance problems (see addEquation(NominalTerm, NominalTerm, boolean)) and given atoms/nabla (see start(Collection, FreshnessCtx)).
boolean	putAtom(DebugLevel debugLevel, PrintStream out, Atom lAtom, Atom rAtom)
void	start(Collection<? extends Atom> atoms, FreshnessCtx nablaIn) Initializes the permutation computation.
String	toString()

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

EquivarianceSystem

public EquivarianceSystem(NodeFactory factory)

EquivarianceSystem

public EquivarianceSystem(NodeFactory factory,
                  EquationSystem<EquivarianceProblem> problemSet)

Method Detail

addEquation

public void addEquation(NominalTerm eq1Left,
               NominalTerm eq2Left,
               boolean deepCopy)

Adds a matching problem to the problem set.

clear

public EquivarianceSystem clear()

compute

public Permutation compute()

Computes the equivariance permutation silently.

See Also:

compute(DebugLevel, PrintStream)

compute

public Permutation compute(DebugLevel debugLevel,
                  PrintStream out)
                    throws ControlledException

Computes an equivariance permutation for given equivariance problems (see addEquation(NominalTerm, NominalTerm, boolean)) and given atoms/nabla (see start(Collection, FreshnessCtx)). Returns null if a clash appears, otherwise a Permutation will be returned.

Throws:

ControlledException

putAtom

public boolean putAtom(DebugLevel debugLevel,
              PrintStream out,
              Atom lAtom,
              Atom rAtom)

start

public void start(Collection<? extends Atom> atoms,
         FreshnessCtx nablaIn)

Initializes the permutation computation.

toString

public String toString()

Overrides:

toString in class Object