Drexel dragonThe Math ForumDonate to the Math Forum



Search All of the Math Forum:

Views expressed in these public forums are not endorsed by Drexel University or The Math Forum.


Math Forum » Discussions » sci.math.* » sci.math.independent

Topic: Getting an element of a disjoint set?
Replies: 3   Last Post: Feb 11, 2014 11:33 AM

Advanced Search

Back to Topic List Back to Topic List Jump to Tree View Jump to Tree View   Messages: [ Previous | Next ]
Victor Porton

Posts: 523
Registered: 8/1/05
Getting an element of a disjoint set?
Posted: Feb 9, 2014 10:58 AM
  Click to see the message monospaced in plain text Plain Text   Click to reply to this topic Reply

Suppose I have disjoint union of sets A and B.

I want to access a particular element of this disjoint union. (For example I
need to check whether an given element is of A or of B.)

What is a good informal notation for this?

Computer proof assistants use data structures to represent disjoint union,
with symbolic field names (like structures in programming languages). But in
informal mathematics (following ZFC pattern) using identifiers is not
customary. Instead they refer to element 0 for A and 1 for B. This is not
aligned well with human perception and intuition.

How would you advise to denote this? (without going too formal)

--
Victor Porton - http://portonvictor.org



Point your RSS reader here for a feed of the latest messages in this topic.

[Privacy Policy] [Terms of Use]

© Drexel University 1994-2014. All Rights Reserved.
The Math Forum is a research and educational enterprise of the Drexel University School of Education.