Results with the hyper_hips tag without the huge_hips tag will not appear when a user searchs the huge_hips tag, nor get it when someone tags a post with huge_hips, but without the latter.
The tag kinda resides on slight proportion variations, but a person searching for huge_hips might also be interested in getting hyper_hips results, the same way hyper_thighs can get results from huge_thighs, hyper_breasts from huge_breasts, etc.
The quantity of results that have this problem is quite large, and making the implication would fix it for the current posts that have one of the tags and is missing the other.