Content deleted Content added
m →Preference relations: fixed umlauts |
m Open access bot: url-access updated in citation with #oabot. |
||
(42 intermediate revisions by 26 users not shown) | |||
Line 1:
{{Short description|Subfield of machine learning}}
'''Preference learning''' is a subfield of [[machine learning]] that focuses on modeling and predicting preferences based on observed preference information.<ref>{{Cite Mehryar Afshin Ameet 2012}}</ref> Preference learning typically involves [[supervised learning]] using datasets of pairwise preference comparisons, rankings, or other preference information.
==Tasks==
The main task in preference learning concerns problems in "[[learning to rank]]". According to different types of preference information observed, the tasks are categorized as three main problems in the book ''Preference Learning''
===Label ranking===
Line 11 ⟶ 10:
In label ranking, the model has an instance space <math>X=\{x_i\}\,\!</math> and a finite set of labels <math>Y=\{y_i|i=1,2,\cdots,k\}\,\!</math>. The preference information is given in the form <math>y_i \succ_{x} y_j\,\!</math> indicating instance <math>x\,\!</math> shows preference in <math>y_i\,\!</math> rather than <math>y_j\,\!</math>. A set of preference information is used as training data in the model. The task of this model is to find a preference ranking among the labels for any instance.
It was observed that some conventional [[Classification in machine learning|classification]] problems can be generalized in the framework of label ranking problem
===Instance ranking===
Line 29 ⟶ 28:
If we can find a mapping from data to real numbers, ranking the data can be solved by ranking the real numbers. This mapping is called [[utility function]]. For label ranking the mapping is a function <math>f: X \times Y \rightarrow \mathbb{R}\,\!</math> such that <math>y_i \succ_x y_j \Rightarrow f(x,y_i) > f(x,y_j)\,\!</math>. For instance ranking and object ranking, the mapping is a function <math>f: X \rightarrow \mathbb{R}\,\!</math>.
Finding the utility function is a [[Regression analysis|regression]] learning problem{{citation needed|date=March 2025}} which is well developed in machine learning.
===Preference relations===
The binary representation of preference information is called preference relation. For each pair of alternatives (instances or labels), a binary predicate can be learned by conventional supervised learning approach. Fürnkranz and Hüllermeier proposed this approach in label ranking problem.<ref name=":0">{{Cite book |last1=Fürnkranz |first1=Johannes |last2=Hüllermeier |first2=Eyke |chapter=Pairwise Preference Learning and Ranking |series=Lecture Notes in Computer Science |date=2003 |volume=2837 |editor-last=Lavrač |editor-first=Nada |editor2-last=Gamberger |editor2-first=Dragan |editor3-last=Blockeel |editor3-first=Hendrik |editor4-last=Todorovski |editor4-first=Ljupčo |title=Machine Learning: ECML 2003 |chapter-url=https://link.springer.com/chapter/10.1007/978-3-540-39857-8_15 |language=en |___location=Berlin, Heidelberg |publisher=Springer |pages=145–156 |doi=10.1007/978-3-540-39857-8_15 |isbn=978-3-540-39857-8}}</ref> For object ranking, there is an early approach by Cohen et al.<ref>{{Cite journal |last1=Cohen |first1=William W. |last2=Schapire |first2=Robert E. |last3=Singer |first3=Yoram |date=1998-07-31 |title=Learning to order things |url=https://dl.acm.org/doi/10.5555/302528.302736 |journal=NeurIPS |series= |___location=Cambridge, MA, USA |publisher=MIT Press |pages=451–457 |doi= |isbn=978-0-262-10076-2}}</ref>
Using preference relations to predict the ranking will not be so intuitive. Since observed preference relations may not always be transitive due to inconsistencies in the data, finding a ranking that satisfies all the preference relations may not be possible or may result in multiple possible solutions. A more common approach is to find a ranking solution which is maximally consistent with the preference relations. This approach is a natural extension of pairwise classification.<ref name=":0" />
==Uses==
Preference learning can be used in ranking search results according to feedback of user preference. Given a query and a set of documents, a learning model is used to find the ranking of documents corresponding to the [[relevance (information retrieval)|relevance]] with this query. More discussions on research in this field can be found in [[Tie-Yan Liu]]'s survey paper.<ref>{{Cite
Another application of preference learning is [[recommender systems]].<ref>{{Citation
==References==
{{Reflist
[[Category:Information retrieval techniques]]
[[Category:Machine learning]]
|