# How can an artificial neural network ANN, be used for unsupervised clustering?

I understand how an artificial neural network (ANN), can be trained in a supervised manner using backpropogation to improve the fitting by decreasing the error in the predictions. I have heard that an ANN can be used for unsupervised learning but how can this be done without a cost function of some sort to guide the optimization stages? With k-means or the EM algorithm there is a function for which each iteration searches to increase.

• How can we do clustering with an ANN and what mechanism does it use to group data points in the same locality?

(and what extra capabilities are brought with adding more layers to it?)

• Are you interested in NN unsupervised learning in general, or specifically in unsupervised clustering with neural networks? – Denis Tarasov Mar 3 '15 at 16:44
• @DenisTarasov, I am interested primarily in unsupervised clustering with NN, but do not know much about NN unsupervised NN learning in general. It would be great if an answer would include a bit of the NN unsupervised learning in general before discussing the specific application. – Vass Mar 3 '15 at 17:02
• Self Organizing Map (SOM) is a type of network used for clustering. – Cagdas Ozgenc Mar 3 '15 at 17:16
• unsupervised learning in ANN – It extracts statistical properties from the training set. – Unsupervised learning is more difficult but is seen as biologically plausible - Requires no teacher. – yonas Apr 3 '17 at 1:29