computation

Unicode's transliteration rules are Turing-complete

a month ago

Unicode UTS #35 transliteration rules, under their natural unbounded semantics, allow universal computation, a result not previously published.
These rules are used in locale data in ICU, a widely used Unicode/globalization library, and termination on a given input is undecidable.
Transliteration rules include features like contexts, capture groups, quantifiers, and a revisiting cursor, enabling complex rewriting operations.
A 2-tag system can be compiled into transliteration rules, proving universality by simulating models like the Collatz function.