Good point, but what ways are there to solve this problem and why solve it? Having 4 different tags for RoR show up under an item is probably not a good idea for a variety of reasons. One of the problems would that some items might be tagged with only 'RoR' and not 'Ruby on Rails' resulting in the user having to aggregate more tags to get a fulfilling search. However the point you make is valid, so it is a problem which should be looked into imo.
Maybe an implementation of an underlying thesaurus could solve this? It might however be hard to maintain it. Any other ideas for how to solve this problem?
Yes an underlying tag thesaurus would be good. Or tag synonyms as leepowers called (I think) the same idea above.
Just to state here a metric for what the end goal is, whatever method is used would ideally provide the same or a pretty similar hit list for any searches for different synonyms with the same meaning.
Maybe an implementation of an underlying thesaurus could solve this? It might however be hard to maintain it. Any other ideas for how to solve this problem?