EXPLANATION IN RECOMMENDER SYSTEMS has been confirmed as the recommended case. Any case that equals the current similarity of the target case at this stage is also recom- As well as being able to explain the relevance of any question asks the user, Top Case can explain why it is recommending a par ticular case. Both types of explanation are dynamically generated at run time using explanation templates. The template used by Top Case to explain the relevance of a question the user is asked depends on whether or not the question has the potential to confirm the target case as the recommended case. Usually in the early stages of query elicitation, the selected attribute can at best be expected to increase the number of cases dominated by the target case rather than confirm the target case outright. The explanation template used when the tar get case cannot be confirmed in a single step Because if a=v this will increase the similarity of Case X from St to S2 and eliminate N cases [including Cases X1, X2,..., X,Jh where a is the attribute whose preferred value the user is asked to specify, U is the value of a in the target case Case X is the target case, SI is the similarity of the target case to the current query, S2 is the similarity of the target case that will result if the preferred value of a is v is the number of cases that will be eliminated if the preferred value of a is u CasesX1, X2,..., X, are cases that the user was shown on the pre- vious recommendation cycle that will be eliminated if the preferred value of a The section of the template enclosed in curly brackets is used only if one or more cases will be eliminated if the preferred value of a is v, which may not be the case in the early stages of query elicitation The section enclosed in square brackets is used only if one or more of the cases that the user was shown in the previous recommendation cycle will be eliminated if the preferred value of a is u The template used by Top Case to explain the relevance of a qu that does have the potential to confirm the target case in a single step is Because if a=u this will confirm case x as the recommended case where a,v, and Case X are as defined for the previous template.EXPLANATION IN RECOMMENDER SYSTEMS 189 has been confirmed as the recommended case. Any case that equals the current similarity of the target case at this stage is also recom￾mended. As well as being able to explain the relevance of any question it asks the user, Top Case can explain why it is recommending a par￾ticular case. Both types of explanation are dynamically generated at run time using explanation templates. The template used by Top Case to explain the relevance of a question the user is asked depends on whether or not the question has the potential to confirm the target case as the recommended case. Usually in the early stages of query elicitation, the selected attribute can at best be expected to increase the number of cases dominated by the target case rather than confirm the target case outright. The explanation template used when the tar￾get case cannot be confirmed in a single step is: Because if a = v this will increase the similarity of Case X from S1 to S2 {and eliminate N cases [including Cases X1, X2,... ,Xr]} where: • a is the attribute whose preferred value the user is asked to specify, • v is the value of a in the target case, • Case X is the target case, • S1 is the similarity of the target case to the current query, • S2 is the similarity of the target case that will result if the preferred value of a is v, • N is the number of cases that will be eliminated if the preferred value of a is v, • CasesX1, X2,... ,Xr are cases that the user was shown on the pre￾vious recommendation cycle that will be eliminated if the preferred value of a is v. The section of the template enclosed in curly brackets is used only if one or more cases will be eliminated if the preferred value of a is v, which may not be the case in the early stages of query elicitation. The section enclosed in square brackets is used only if one or more of the cases that the user was shown in the previous recommendation cycle will be eliminated if the preferred value of a is v. The template used by Top Case to explain the relevance of a question that does have the potential to confirm the target case in a single step is: Because if a = v this will confirm Case X as the recommended case where a, v, and Case X are as defined for the previous template