artificial-intelligencemachine-learningneural-network

Is a neural network a lazy or eager learning method?


Is a neural network a lazy or eager learning method? Different web pages say different things so I want to get a solid answer with good literature to back it up. The most obvious book to look in would be Mitchell's famous Machine Learning book but skimming through the whole thing I can't see the answer. Thanks :).


Solution

  • Looking at the definition of the terms lazy and eager learning, and knowing how a neural network works, I believe that it is clear that it is eager. A trained network is a generalisation function, all the weights and paths used to arrive at a classification are entirely determined by training data, but the training data itself is not retained for the purposes of the decision making.

    An important distinction is that a Lazy system stores its training data and uses it directly to determine a solution. An eager system determines a function from the training data, and thereafter the training data is no longer required. That is to say you cannot determine what the training data was from an eager system's function. A neural network certainly fits that description. An eager system can therfore be very storage efficient, but conversely is non-deterministic, in the sense that it is not possible to determine how or why it arrived a a particular solution, so problems of poor or inappropriate training data may be difficult deal with.

    The eager article linked above even gives artificial neural networks as an example. You might of course prefer a cited text to Wikipedia but the page has existed with that assertion since 2007 without contradictory edits, so I'd say that was pretty robust.