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29 votes

A relation $R$ is defined on ordered pairs of integers as follows: $$(x,y)R(u,v) \text{ if } x<u \text{ and } y>v$$ Then $R$ is:

- Neither a Partial Order nor an Equivalence Relation
- A Partial Order but not a Total Order
- A total Order
- An Equivalence Relation

1)Given relation (x,y)R(u,v) if x<u and y>v

is not reflexive, not symmetric, transitive, Irreflexive, Antisymmetric, Asymmetric. It is not partial order nor equivalence relation. See @AyushUpadhyaya comment below for more info.

2)If question was like relation (x,y)R(u,v) if x<=u and y>=v

then it is reflexive,Antisymmetric, transitive. So, Partial order.

But not total order because neither (0,0)R(2,2) nor (2,2)R(0,0).

It is not equivalence relation also.

It is reflexive, not symmetric, transitive, not Irreflexive, Antisymmetric, not Asymmetric.

Please, correct if anything is wrong here.

3

34 votes

Best answer

edited
Jun 29, 2018
by Ayush Upadhyaya

For reflexivity, (X,Y) R (X,Y) , which here requires x<x and y<y and this is not possible in this relation.

This relations is Not Symmetric as

$(x,y)R(u,v)$ iff x<u and y>v

$(u,v)R(x,y)$ iff u<x and v>y completly opposite conditions!!

Since, reflexive and symmetric pairs are not allowed, the matrix of this relation would contain only either lower triangular or upper triangular elements as 1.

So this relation is Anti-Symmetric.

This relation is Irreflexive as not even a single case of reflexivity is possible.

Since the relation is Irreflexive and Anti-Symmetric, it is Asymmetric.

This relation is also transitive as

$(x,y)R(u,v)$ iff x<u and y>v

$(u,v)R(a,b)$ iff u<a and v>b

both imply

x<u<a and y>v>b

implies

x<a and y>b which makes (x,y)R(a,b)

Hence, transitive.

This relations is Not Symmetric as

$(x,y)R(u,v)$ iff x<u and y>v

$(u,v)R(x,y)$ iff u<x and v>y completly opposite conditions!!

Since, reflexive and symmetric pairs are not allowed, the matrix of this relation would contain only either lower triangular or upper triangular elements as 1.

So this relation is Anti-Symmetric.

This relation is Irreflexive as not even a single case of reflexivity is possible.

Since the relation is Irreflexive and Anti-Symmetric, it is Asymmetric.

This relation is also transitive as

$(x,y)R(u,v)$ iff x<u and y>v

$(u,v)R(a,b)$ iff u<a and v>b

both imply

x<u<a and y>v>b

implies

x<a and y>b which makes (x,y)R(a,b)

Hence, transitive.

36

15 votes

Just take an eg. of 3 elements. Let set A={0,1,2}

Find out the relation set according to qs.

Relation R ={ ((0,1),(1,0)) , ((1,2),(2,1)) , ((0,1),(2,0)) , ((0,2),(1,0)) , ((0,2),(1,1)) , ((0,2),(2,1)) , ((1,2),(2,0)) , ((1,2),(2,1)) }

Check properties of relation R :

1.Reflexive = NO

2.Symmetric = NO

3.Transitivity = YES

4.Antisymmetric = Yes

So according to properties of POR and Equivalence relation it is neither POR nor Equivalence relation.

12 votes

An **equivalence relation** on a set x is a subset of x*x, i.e., a collection R of ordered pairs of elements of x, satisfying certain properties. Write “x R y” to mean (x,y) is an element of R, and we say “x is related to y,” then the properties are

1. Reflexive: a R a for all a Є R,

2. Symmetric: a R b implies that b R a for all a,b Є R

3. Transitive: a R b and b R c imply a R c for all a,b,c Є R.

An **partial order**** relation** on a set x is a subset of x*x, i.e., a collection R of ordered pairs of elements of x, satisfying certain properties. Write “x R y” to mean (x,y) is an element of R, and we say “x is related to y,” then the properties are

1. Reflexive: a R a for all a Є R,

2. Anti-Symmetric: a R b and b R a implies that for all a,b Є R

3. Transitive: a R b and b R c imply a R c for all a,b,c Є R.

An **total order**** relation** a set x is a subset of x*x, i.e., a collection R of ordered pairs of elements of x, satisfying certain properties. Write “x R y” to mean (x,y) is an element of R, and we say “x is related to y,” then the properties are

1. Reflexive: a R a for all a Є R,

2. Anti-Symmetric: a R b and b R a implies that for all a,b Є R

3. Transitive: a R b and b R c imply a R c for all a,b,c Є R.

4. Comparability : either a R b or b R a for all a,b Є R.

As given in question, a relation R is defined on ordered pairs of integers as follows: (x,y) R(u,v) if x < u and y > v , reflexive property is not satisfied here , because there is > or < relationship between (x ,y) pair set and (u,v) pair set . Other way , if there would have been x <= u and y>= v (or x=u and y=v) kind of relation amongs elements of sets then reflexive property could have been satisfied. Since reflexive property in not satisfied here , so given realtion can not be **equivalence ,****partial order**** ****or t****otal order ****relation.**So ,Answer (A) is true