Suppose I know nothing about Chinese writing systems but some basic strokes and radicals. When given a blocky-looking character, how do I tell if it's a character only used in Kanji, in Chữ Nôm, or in Chinese?
Of course, we can also consider Sawndip, Tangut, Khitan, etc.
Clues I can think of:
- Chữ Nôm uses quite some radicals at places that Chinese characters won't use. For example, 𡨸 (Chữ in Chữ Nôm) uses 宁 as a left-side radical, which is never seen in Chinese.
- Simplified Chinese uses "又" quite often. For example, the traditional Chinese character 漢 (han in han zi) is simplified to 汉.
- Tangut and Khitan uses the two crossing strokes 乂 quite liberally.
EDIT: Updated the title to clarify that I'm looking for heuristics, rather than an "algorithm" that will prove 100% correct.
Disclaimer: As a native Chinese speaker who have learned Japanese and is recently dipping into Vietnamese, I found my own judgement biased and suffering from the curse of knowledge in coming up with an answer.