# Re: The seven step series

From: m.a. <marty684.domain.name.hidden>
Date: Sat, 4 Jul 2009 09:17:06 -0400

Bruno,
Can you provide definitions of "belongs-to" and "included-in" that distinguish them from "union" and "intersection"?

Here we met a set of sets.
The set of subsets of a set, can only be, of course, a set of sets. The set {2, 21, 14} is a set of numbers. The set { { }, {4, 78, 56} } is a set of sets. It has two elements: the empty set {}, and the set of numbers {4, 78, 56}. Do not confuse a number, like 24, and a set, like {24}, which is a set having a number has elements. In particular it is the case that {4, 78, 56} belongs to { { }, {4, 78, 56} }. Take it easy, and meditate on the following exercise:

Which of the following are true

{3, 5} included-in {3, 5} True
{3, 5} belongs-to {3, 5}
{3, 5} included-in { {3, 5} }
{3, 5} belongs-to { {3, 5} }

Bruno

http://iridia.ulb.ac.be/~marchal/

--~--~---------~--~----~------------~-------~--~----~
You received this message because you are subscribed to the Google Groups "Everything List" group.
To post to this group, send email to everything-list.domain.name.hidden
To unsubscribe from this group, send email to everything-list+unsubscribe.domain.name.hidden
For more options, visit this group at http://groups.google.com/group/everything-list?hl=en
-~----------~----~----~----~------~----~------~--~---
Received on Sat Jul 04 2009 - 09:17:06 PDT

This archive was generated by hypermail 2.3.0 : Fri Feb 16 2018 - 13:20:16 PST