is it possible to do feature selection for unsupervised machine learning problems? I started looking for ways to do feature selection in machine learning. 

By having a quick look at this  post , I made the assumption that feature selection is only manageable for supervised learning problems:



Still, I have to ask: are there methods to do feature selection without having a known variable that will be used for a classification/regression problem?
Take a look at these links-

https://stats.stackexchange.com/questions/108743/methods-in-r-or-python-to-perform-feature-selection-in-unsupervised-learning

http://www.jmlr.org/papers/volume5/dy04a/dy04a.pdf

https://www.researchgate.net/post/What_is_the_best_unsupervised_method_for_feature_subset_selection