Idea-to-idea search for arXiv.
Search the whole arXiv corpus by what a paper does, not what it calls it.
Search arXiv freeType the problem you are stuck on in your own words. FKS matches on the idea underneath: the problem a paper solves, or what its result makes newly possible. Papers that share none of your terminology still come back. There is no account and no cost. This is an open beta, so rankings still change week to week.