Sets & Notation: Homework Explained

In summary, the conversation discusses the meaning of T: R x R -> R and A \subseteq B in terms of sets and functions. The use of Cartesian product and operations is explained and it is clarified that A \subseteq B does not necessarily mean that A and B are the same set.
  • #1
Niles
1,866
0

Homework Statement


Hi all.

If I have a set R and a function T, then what does the following mean: T: R x R -> R?

Also, when I have a set A and a set B, then does the following mean that all elements in A are equal to all elements in B? A [itex]\subseteq[/itex] B
 
Physics news on Phys.org
  • #2
Niles said:

Homework Statement


Hi all.

If I have a set R and a function T, then what does the following mean: T: R x R -> R?
RxR, the Cartesian product, is the set of all pairs, (x,y), where each of x and y is in R. T: R x R->R means that T is a function that, to every such pair, (x,y), assigns a member of R.

Operations are often represented that way. For example, if R is the set of real numbers, R x R is the set of pairs of real numbers and addition, "+", assigns a single number to every pair of numbers: T(x,y)= x+ y so T: R x R-> R.

Also, when I have a set A and a set B, then does the following mean that all elements in A are equal to all elements in B? A [itex]\subseteq[/itex] B
No, not if by "all elements in A are equal to all elements in B" you mean they are the same set. [itex]A \subset A[/itex] means that all elements of A are in B, but there are some elements of B that are not in A. [itex]A\subseteq B[/itex] includes the possibility that there are no elements of B that are not in A- the possiblility that A= B.
 
  • #3
Thank you. Two very good answers for two questions.

That cleared things up.
 

FAQ: Sets & Notation: Homework Explained

What is a set?

A set is a collection of distinct objects or elements. These objects can be anything from numbers, letters, to even complex mathematical expressions. Sets are often denoted by curly braces and each element is separated by a comma.

What is the difference between a set and a subset?

A set is a collection of elements, while a subset is a set that contains elements from another set. In other words, all elements in a subset are also found in the original set, but the original set may contain additional elements.

What is the cardinality of a set?

The cardinality of a set is the number of elements in the set. It is denoted by |S|, where S is the set. For example, if a set S = {1, 2, 3}, then |S| = 3.

What is the difference between a union and intersection of sets?

The union of two sets, denoted by ∪, is the set of all elements that are in either set. The intersection of two sets, denoted by ∩, is the set of all elements that are in both sets. In other words, the union includes all elements from both sets, while the intersection only includes elements that are common to both sets.

What is the difference between an element and a member of a set?

An element refers to an individual object or value within a set, while a member of a set refers to the set itself. For example, in the set A = {1, 2, 3}, 1 is an element of the set, while A is a member of the set of all sets.

Back
Top