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Daniel Fortunov's Blog » GEB Chapter 1: The MU-Puzzle

Back to Daniel Fortunov's Blog Written on 21-May-2008 by asqui

The real first chapter of Gödel, Escher, Bach is an introduction to Formal Systems^[?] (what I previously thought was Chapter 1 was actually an introduction to the entire book).

Here's a puzzle from that chapter:

Given the starting string "MI", what is the quickest way to turn it into the string "MU" using only the following rules: (where x and y represent any string)

Any string ending in I may have U appended to the end:
xI → xIU (e.g. MI → MIU)
Any string beginning with M can have the following letters doubled:
Mx → Mxx (e.g. MIU → MIUIU)
Any occurrence of III may be replaced with U:
xIIIy → xUy (e.g. MIUIII → MIUU)
Any occurrence of UU may be removed:
xUUy → xy (e.g. MIUU → MI)

Answers on the back of a postcard; Prizes for the correct solution.

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Tags: puzzle,geb

Comments

written on 21-May-2008

chickerino [http://www.chickerino.com] says:

What is the prize? I need to work out whether its worth looking up the answer on google
written on 22-May-2008

Phailanx [http://www.phailanx.co.uk] says:

The answer is 3

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Daniel Fortunov's Blog » GEB Chapter 1: The MU-Puzzle

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