According to the wiki for cardigan, it's a kind of sweater, but they're both very big tags, so I figured I'd ask before putting in an implication. Is there a reason there's no formal relationship between the two tags?
Sorry, but I guess that cardigan implicating sweater is somehow unnecessary. For the sake of searchability and preventing redundancy, I guess. On the same manner why wouldn't school uniform imply uniform. Or how underwear, lingerie, bra etc. do not imply revealing clothes (I cannot explain exactly why despite I read the wiki). Or the reason why my BUR for tank to imply armored vehicle was not approved despite being obvious - the armored vehicle tag was meant to specify any other type of non-tank combat vehicles.