secret code in which every letter is replaced by a word with max 10 letters
Source: TOT 564 1997 Autumn S A5
September 11, 2024
combinatorics
Problem Statement
Dima invented a secret code in which every letter is replaced by a word no longer than letters. A code is called “good” if every encoded word can be decoded in only one way. Serjozha (with the help of a computer) checked that for Dima’s code, every possible word of at most letters can be decoded in only one way. Does it follow that Dima’s code is good? (Note that Dima and Serjozha are Russian, so they use the Cyrillic alphabet, which has letters! A word is any sequence of letters.)(D Piontkovskiy, S Shalunov)