This paper synthesizes a number of approaches to concept representation and learning in a multilayered model. The paper emphasizes what has been called similarity-based learning (SBL) from examples, although this review is extended to address wider issues. The paper pays particular attention to requirements for incremental and uncertain environments. and to interrelationships among concept purpose, concept representation, and concept learning.One goal of the paper is to unite some of the notions underlying recent research, in an attempt to construct a more complete and extensible framework. This framework is designed to capture representations and methods such as those based on hypothesis search and bias selection, and to extend the ideas for greater system capability. This leads to a specific perspective for multilayered learning which has several advantages, such as greater clarity, more uniform learning, and more powerful induction.The approach clarifies and unifies various aspects of the problem of concept learning. Some results*are (1) Various concept representations (such as logic, prototypes, and decision trees) are subsumed by a standard form which is well suited to learning, particularly in incremental and uncertain environments;(2) Concept leaming may be enhanced by exploiting a particular phenomenon in many spaces-this phenomenon is a certain kind of smoothness or regularity, one instance of which underlies the similarity in SBL systems; (3) The paper treats the phenomenon in a general way and applies it hierarchically.This has various advantages of uniformity. For example the model allows layered leaming algorithms for concept learning all .to be instantiations of one basic algorithm. A single kind of representation (an instantiation of the standard form) is prominent at each level. The combination of representation and algorithm allows fast, accurate, concise, and robust concept learning.Le pdsent article fait la synthese d'un certain nombre de mtthodes de repdsentation et d'apprentissage des concepts dans un modtle multicouche. L'auteur insiste sur ce qu'on a appelt I'apprentissage par dttection dc similarit& (ADS) en pdsentant des exemples; son point de vue s'ttend toutefois ti des sujets plus vastes. Il p e t e particulibrement attention aux exigences relatives aux environnements incdmentiels et incertains, ainsi qu'B la codlation entre le but, la rep6entation et I'apprentissage des concepts.Cet article vise notamment i unifier certaines des notions qui sont ti la base des recherches dcentes, afin que soit tdifik un cadre plus complet et plus extensible. Cette structure est cogue pour reproduire des repdsentations et des mtthodes, comme celles bastes sur la recherche d'hypothtses et la stlection de polarisations, et pour tlargir les id& ayant pour but d'accroitre le potentiel des systkmes. Cela conduit i envisager une perspective sptcifique au niveau de I'apprentissage rnulticouche, ce qui pnkente plusieurs avantages : plus grande pkcision, uniformisation de l'apprentissage et augmentation de la ...