BUR #12871 has been approved by @nonamethanks.
create alias sweatshirt -> sweater
For danbooru's purposes, sweatshirt and sweater are the same thing. Any attempt at distinguishing them is pointless because they are synonyms for most people (as shown by the usage of these tags), and 99% of them are going to look the same in anime art. There's already more descriptive tags for specific variants of sweaters like ribbed sweater and aran sweater, so it makes no sense for us to have these two separate when we already lump everything including cardigan (cardigan sweater, whether we like it or not) under sweater. An implication doesn't make sense either because there's no distinguishing feature.
sweatshirt is also a really bad tag name because people will use color_shirt to tag them. See sweatshirt red_shirt for example.
Previous discussions: