To add insult to injury this article hasn’t discovered anything new, makes it sound way more complicated than it is, and in the end still requires you to just remember which verbs are of the eru/iru group, and which are not (which was posed as a problem to solve in the intro).
Just make cards and mark the stem, learn it along with the verb. No need for heuristics. If you ever forget, you’re bound to remember the masu-form and can reverse engineer the stem from that 100%.
Your brains "language module" is not a slow computer, computing rules, it's a fast lookup-table.
And wow.. you did seem to go out of your way to stay ahead of those comments. Respect for that.
And my respect for dissecting this aspect of Japanese grammar. You seemed to be dissatisfied spending time learning something that, in your eyes, wasn't yet condensed to its most basic rule. And I agree with that feeling. It leads to truely understanding how something became, eventually to discovery. Your article reads like you did that research mostly for yourself, but wanted to share what you found. That's a refreshing attitude, although the chances are high that field has been tilled thoroughly by Japanese linguists. I have to say I can't remember having seen any explanation about secret vowels/consonants in Japanese grammar books - I know some. But that may be because 1. I haven't read every there is, 2a. it's sort of doing archaeology on language and/or 2b. it doesn't add much to simplify learning the rules.
I confess my affair with grammar was always a cursory one and that may be because it proved to be so much more effective to go with examples, and pick that conjugation up as a side dish. But that's just me.
Compressing the rules does make sense, but at some point you just have to learn what's there. Language and grammar is always more or less arbitrary. Elegant yes, but arbitrary. It can't be derived from fundamentals. But the payoff makes it a worthwhile endeavor learning a language so strange from English as Japanese: you get a glimpse what the essence of language is. What a great motivation that was and is.
Some things that might spark your interest and keep exploring:
There are ごだん verbs that look like いちだん: 要る, 帰る, 限る, 切る, 知る, 入る, 走る, 滑る
Verbs with the same dictionary form but belonging to different conjugations: 切る/着る, 帰る/変える, 要る/居る, 減る/経る, 湿る/閉める, 練る/寝る
Keep up the good work. Doing research with the door open is a noble endeavor in its own right.
When starting out it is super nice to know stuff like: here is how you say if-then statements, here is how you recommend stuff, here is how make guesses, here is how you quote another person, etc. etc.
That said, I would argue most textbooks get the ratio of the length of the explanation vs. example sentences wrong. For every sentence in the explanation you should have at least three examples.
It's definitely useful to understand how "chi" and "tsu" fit into the hiragana chart, and if your asterisk notation helps you remember which verbs are ichidan vs godan then that's great, but I'm not sure it's worth trying to unify -masu and -nai into one model.
I think you’re taking a lot of stuff for granted. “Just” do cards etc. You’re using the word “stem” but what’s a stem? Why do we sometimes inject -i or -a (or -wa) there and sometimes we don’t? You still have to learn that and understand that. That’s what I’m describing in the article. If you already know stems and how they compose with suffixes, congratulations, you won’t find my article useful.
