I've recently read about concept learning in a machine learning class. They defined a concept as (translated from German):


  • Describes a subset of objects or events defined on a bigger set.
  • Boolean function defined on bigger set

Given: Examples which are labeled as members or not-members

Searched: Automatically infer the definition of the underlying concept

Definition of concept learning: Infering a boolean-valued function from training data of its input and its output.

I would call this a 2-class classification problem. Is there a difference?

  • $\begingroup$ Nice question. Are there any online links, which can help us learn more about the concept of concept learning? $\endgroup$
    – Dawny33
    Commented Dec 2, 2015 at 7:11
  • 1
    $\begingroup$ @Dawny33 Just for reference if others find this question: profsite.um.ac.ir/~monsefi/machine-learning/pdf/… Chapter 2 is about concept learning and this question stems from their definition $\endgroup$
    – WhatAMesh
    Commented Dec 24, 2019 at 23:05

1 Answer 1


The objective is rather different. For classification problems, we want to know: GIVEN X, WHAT WILL BE Y? For concept-learning problems, we are asking: WHAT KIND OF X WILL GIVE US Y?

It may seem similar, but for classification problems, we may use a model that is unable to generalize and answer "WHAT KIND OF X WILL GIVE US Y" until you plug X into the model (e.g. K-nearest neighbor).

On the other hand, concept-learning problems, the main issue is to generalize and answer what can be X specifically.

  • $\begingroup$ Which algorithms would be used for concept learning? $\endgroup$ Commented Nov 2, 2015 at 5:54
  • $\begingroup$ This slide: ml.informatik.uni-freiburg.de/_media/documents/teaching/ss09/ml/… outlined a few algorithms for concept learning $\endgroup$
    – Jacky Ma
    Commented Nov 2, 2015 at 6:04
  • $\begingroup$ So with techniques like the ones used in deep dream / the ones presented by Matt Zeiler in Visualizing and Understanding Deep Neural Networks one can say that the CNN is learning the concept of "cats" and can of course be used to classify images as "cats"? $\endgroup$ Commented Jan 7, 2016 at 10:53
  • $\begingroup$ It still seems to me that any learning algorithm for classification can be used to generate instances of the class. Hence all classification algorithms would also be concept learning algorithms? $\endgroup$ Commented Jan 7, 2016 at 10:54
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    $\begingroup$ No. classification only has a model p(y|x), so can't generate x's given y -- p(x|y). You could do that with a generative model only, which learns p(x,y), like naive bayes for example. Maybe this is what concept learning is in modern terminology? $\endgroup$
    – samlaf
    Commented Aug 9, 2019 at 15:17

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