Discrete Mathematics with Applications 4th Edition

Published by Cengage Learning
ISBN 10: 0-49539-132-8
ISBN 13: 978-0-49539-132-6

Chapter 6 - Set Theory - Exercise Set 6.4 - Page 382: 24

Answer

The definition of n leads to a contradiction because it describes n in fewer than 12 words, even though n is defined as being indescribable in fewer than 12 words. This is Berry’s paradox — a contradiction arising from self-reference and definability.

Work Step by Step

This is a famous logical puzzle known as **Berry’s Paradox**. --- ### Given: Let \[ n = \text{“the smallest integer not describable}\\ \text{ in fewer than 12 English words.”} \] The problem: There are only **finitely many** strings of 11 or fewer English words, so only **finitely many integers** can be described that way. Thus, there must be some smallest integer not so describable — so \(n\) should exist. But now… --- ### ❗ The Paradox: The phrase > “the smallest integer not describable in fewer than 12 English words” **is itself a description of \(n\)** — and it **contains only 11 words**! So we have: - \(n\) **cannot** be described in fewer than 12 words (by its own definition), - but we just **described it** in 11 words. This creates a **contradiction**. --- ### 🌀 Why It Happens: The contradiction arises because the **definition** refers to what is **definable**, creating a **self-referential** loop. This is similar in spirit to: - Russell’s paradox (set of all sets that don’t contain themselves), - the liar paradox (“This sentence is false.”), - and Gödel’s incompleteness theorems (limits of formal systems to fully describe themselves).
Update this answer!

You can help us out by revising, improving and updating this answer.

Update this answer

After you claim an answer you’ll have 24 hours to send in a draft. An editor will review the submission and either publish your submission or provide feedback.