de.learnlib.algorithm.lstar.closing.CloseRandomStrategy Maven / Gradle / Ivy

Go to download

Show more of this group Show more artifacts with this name
Show all versions of learnlib-lstar Show documentation

This artifact provides the implementation of the L* learning algorithm described in the paper "Learning Regular Sets from Queries and Counterexamples" (https://doi.org/10.1016/0890-5401(87)90052-6) by Dana Angluin including variations and optimizations thereof such as the versions based on "On the Learnability of Infinitary Regular Sets" (https://dx.doi.org/10.1006/inco.1995.1070) by Oded Maler and Amir Pnueli or "Inference of finite automata using homing sequences" (http://dx.doi.org/10.1006/inco.1993.1021) by Ronald L. Rivest and Robert E. Schapire.

The newest version!

/* Copyright (C) 2013-2023 TU Dortmund
 * This file is part of LearnLib, http://www.learnlib.de/.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package de.learnlib.algorithm.lstar.closing;

import java.util.ArrayList;
import java.util.List;
import java.util.Random;

import de.learnlib.datastructure.observationtable.ObservationTable;
import de.learnlib.datastructure.observationtable.Row;
import de.learnlib.oracle.MembershipOracle;
import org.checkerframework.checker.nullness.qual.Nullable;

public class CloseRandomStrategy implements ClosingStrategy<@Nullable Object, @Nullable Object> {

    private final Random random;

    public CloseRandomStrategy() {
        this(new Random());
    }

    public CloseRandomStrategy(Random random) {
        this.random = random;
    }

    @Override
    public  List> selectClosingRows(List>> unclosedClasses,
                                                    ObservationTable table,
                                                    MembershipOracle oracle) {
        List> result = new ArrayList<>(unclosedClasses.size());

        for (List> clazz : unclosedClasses) {
            int card = clazz.size();
            result.add(clazz.get(random.nextInt(card)));
        }

        return result;
    }

    @Override
    public String toString() {
        return "CloseRandom";
    }

}