/**
* Copyright (c) 2011, SOCIETIES Consortium (WATERFORD INSTITUTE OF TECHNOLOGY (TSSG), HERIOT-WATT UNIVERSITY (HWU), SOLUTA.NET
* (SN), GERMAN AEROSPACE CENTRE (Deutsches Zentrum fuer Luft- und Raumfahrt e.V.) (DLR), Zavod za varnostne tehnologije
* informacijske družbe in elektronsko poslovanje (SETCCE), INSTITUTE OF COMMUNICATION AND COMPUTER SYSTEMS (ICCS), LAKE
* COMMUNICATIONS (LAKE), INTEL PERFORMANCE LEARNING SOLUTIONS LTD (INTEL), PORTUGAL TELECOM INOVAÇÃO, SA (PTIN), IBM Corp.,
* INSTITUT TELECOM (ITSUD), AMITEC DIACHYTI EFYIA PLIROFORIKI KAI EPIKINONIES ETERIA PERIORISMENIS EFTHINIS (AMITEC), TELECOM
* ITALIA S.p.a.(TI), TRIALOG (TRIALOG), Stiftelsen SINTEF (SINTEF), NEC EUROPE LTD (NEC))
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following
* conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following
* disclaimer in the documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING,
* BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
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*/
package org.societies.privacytrust.trust.api.similarity;
import org.societies.api.privacytrust.trust.model.TrustedEntityId;
/**
* This interface provides methods to evaluate the similarity of users
* based on their direct trust relationships.
*
* @author <a href="mailto:nicolas.liampotis@cn.ntua.gr">Nicolas Liampotis</a> (ICCS)
* @since 1.1
*/
public interface ITrustSimilarityEvaluator {
/**
* Evaluates the cosine similarity between the given trustor and trustee.
* More specifically, the resulting similarity ranges from −1 meaning
* exactly opposite, to 1 meaning exactly the same, with 0 usually
* indicating independence, and in-between values indicating intermediate
* similarity or dissimilarity.
*
* @param trustorId
* the entity to compare against the given trustee.
* @param trusteeId
* the entity to compare against the given trustor.
* @return the cosine similarity between the given trustor and trustee.
* @throws TrustSimilarityEvalException
* if there is a problem evaluating the cosine similarity.
* @throws IllegalArgumentException
* if the specified identifiers are not of type CSS.
* @throws NullPointerException
* if any of the specified parameters is <code>null</code>.
*/
public Double evaluateCosineSimilarity(final TrustedEntityId trustorId,
final TrustedEntityId trusteeId) throws TrustSimilarityEvalException;
}