All about flooble | fun stuff | Get a free chatterbox | Free JavaScript | Avatars    
perplexus dot info

Home > Logic
Least But Not The Last (Posted on 2003-05-08) Difficulty: 4 of 5
Prove that every Non-Empty set of Positive Integers contains a "Least Element".

See The Solution Submitted by Ravi Raja    
Rating: 2.7500 (8 votes)

Comments: ( Back to comment list | You must be logged in to post comments.)
re: Proof by Contradiction Comment 13 of 13 |
(In reply to Proof by Contradiction by friedlinguini)

I came up with something similar:


Let S be a non-empty set of positive integers. Let I be a binary sequence indexing the integers in S, where bit i of I is 1 if and only if i is in S. For example, if S is {1, 3, 5}, then I is 10101000...

Since S is non-empty, I clearly has a first occurrence of 1 somewhere. That occurrence of 1 clearly corresponds to the least element of S.

  Posted by Caleb on 2019-04-02 23:23:02
Please log in:
Login:
Password:
Remember me:
Sign up! | Forgot password


Search:
Search body:
Forums (0)
Newest Problems
Random Problem
FAQ | About This Site
Site Statistics
New Comments (3)
Unsolved Problems
Top Rated Problems
This month's top
Most Commented On

Chatterbox:
Copyright © 2002 - 2024 by Animus Pactum Consulting. All rights reserved. Privacy Information