stem change verbs
is there a way to tell if a verb is a stem change verb by looking at the infinitive or you just have to memorise it as you go along
Maybe someone has a genius delineation, but I thought you basically just had to memorize them. That said, once you're familiar with the main groups, you'll start to "hear" where others fit in. (Like, even if you didn't learn "hervir" as an e-ie changer, you'll hear that "herves" sounds wrong and will want to make it say "hierves" instead.
Unit Three here is another good resource.