Math Problem Statement

Show that whether the relation (x, y) ∈ R, if, x ≥ y defined on the set of +ve integers is a partial order relation.

Solution

To show that the relation (x,y)R(x, y) \in R, where xyx \geq y is defined on the set of positive integers, is a partial order relation, we must verify that it satisfies the three properties required for a relation to be a partial order:

  1. Reflexivity: For all xZ+x \in \mathbb{Z}^{+} (the set of positive integers), xxx \geq x.
  2. Antisymmetry: For all x,yZ+x, y \in \mathbb{Z}^{+}, if xyx \geq y and yxy \geq x, then x=yx = y.
  3. Transitivity: For all x,y,zZ+x, y, z \in \mathbb{Z}^{+}, if xyx \geq y and yzy \geq z, then xzx \geq z.

Let's check these properties step by step:


1. Reflexivity:

A relation is reflexive if for every element xZ+x \in \mathbb{Z}^{+}, we have (x,x)R(x, x) \in R.

In this case, for every positive integer xx, we have xxx \geq x (since \geq is a reflexive operation). This is true for all xZ+x \in \mathbb{Z}^{+}.

Therefore, the relation \geq is reflexive.


2. Antisymmetry:

A relation is antisymmetric if for all x,yZ+x, y \in \mathbb{Z}^{+}, whenever (x,y)R(x, y) \in R and (y,x)R(y, x) \in R, we must have x=yx = y.

In this case, if xyx \geq y and yxy \geq x, the only way both inequalities can be true simultaneously is if x=yx = y (since both xyx \geq y and yxy \geq x imply equality).

Therefore, the relation \geq is antisymmetric.


3. Transitivity:

A relation is transitive if for all x,y,zZ+x, y, z \in \mathbb{Z}^{+}, whenever (x,y)R(x, y) \in R and (y,z)R(y, z) \in R, it follows that (x,z)R(x, z) \in R.

In this case, if xyx \geq y and yzy \geq z, then by the properties of the inequality, we must have xzx \geq z (since if xyx \geq y and yzy \geq z, then xzx \geq z).

Therefore, the relation \geq is transitive.


Conclusion:

Since the relation \geq on the set of positive integers satisfies reflexivity, antisymmetry, and transitivity, we can conclude that it is a partial order.

Would you like a more detailed explanation of any of these steps, or do you have any further questions?

Here are some related questions for further exploration:

  1. What is the difference between a partial order and a total order?
  2. How do we represent partial orders using Hasse diagrams?
  3. Can you give an example of a set that forms a total order under the relation \leq?
  4. What other relations can be considered partial orders?
  5. How can we check whether a relation is an equivalence relation instead of a partial order?

Tip: When verifying whether a relation is a partial order, always check the three key properties: reflexivity, antisymmetry, and transitivity.

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Math Problem Analysis

Mathematical Concepts

Set Theory
Relations
Partial Orders

Formulas

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Theorems

Reflexivity
Antisymmetry
Transitivity

Suitable Grade Level

Grades 11-12