The Smallest Unambiguous Turing-Complete Language

ι←これ link ね、見えにくいけど。

Why care whether Iota is unambiguous? If ambiguous languages were allowed, we could do without the star, and have an even simpler language:

Syntax Semantics

F --> i ^x.xSK
F --> F F [F][F]

This language has just one symbol, "i"! But every string of length n would have m syntactic analyses, where m is the nth Catalan number, and that seems like cheating to me. Anyway, ambiguous languages are hard to write reliable programs in.[emphasis added]

違う違う、そこは理由にする所じゃない。