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a+b+ means OR in formal RE: a+bAlternationFormal RE✨ Emoji Combos

⚠ In formal RE, + is alternation/union, NOT "one or more". a+b ≡ a|b = {a, b}. This is the biggest syntactic difference from programming regex.

✓ Accepts
ab
✗ Rejects
εabcaaaab
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