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Monday, November 25, 2019

Relation and Functions

Equivalence and partial order relations with examples

 

Equivalence relations:

A relation ‘R’ on set ‘A’ is said to be equivalent if R is 

 

  1. Reflexive. It needs to be diagonal pair such as (a,a),(1,1),(8,8) 
  2. Symmetric: it should have element  such as (a,b) and (b,a) for example (1,4) and (4,1) in the relation set for symmetric
  3. Transitive: It needs to be in the form of (a,b), (b,c) so that we have (a,c)

 

Let us understand with an example

 

A={1,2,3}  elements =2^3 

A(1,1)

A(1,2)

A(1,3)

A(2,1)

A(2,2)

A(2,3)

A(3,1)

A(3,2)

A(3,3)



R1={NULL} it is not reflexive and therefore equivalence does not holds.

R2={(1,1),(2,2) (3,3)} it is reflexive as it has diagonal pairs such as (a,a)

It is symmetric as all diagonal pair makes the set symmetric

Also if also transitive if it has only diagonal elements. 

Therefore the relation is equivalence

R3={(1,1),(2,2) (3,3)(2,1)} It is reflexive as it has all diagonal elements

It is not symmetric as there exist only (2,1) and not (1,2) in R3. There the relation is not in 

equivalence

 

R4={(1,1),(1,3),(2,1)(3,1)} It does not has all diagonal elements ref to table above, hence it does not have equivalence relation

R5={(1,1),(2,2),(3,3),(1,2)(1,3)(2,1)(3,1)} It is reflexive as it has all diagonal elements ref table

It is symmetric as we have (1,2) and (2,1). Also we have (1,3) and (3,1)

 

It is transitive as if we take (1,1) (3,3) then we have (3,1) as in (a,b) and (b,c) we have (a,c) for it to become transitive. Hence equivalence hold here.

R6={(1,1),(1,2),(2,1),(2,3),(3,1)(3,2),(3,3)} It is not reflexive as we do not have all diagonal elements ref table above and you will find (2,2) is missing.



Partial order relations

  1. Reflexive. It needs to be diagonal pair such as (a,a),(1,1),(8,8) 
  2. Anti Symmetric: it should not have element  such as (a,b) and (b,a) for example (1,4) and (4,1) in the relation set for symmetricity. If it has (a,b) and not (b,a) then it is said to be in anti symmetric form
  3. Transitive: It needs to be in the form of (a,b), (b,c) so that we have (a,c)




A=(1,2,3}

 

R1={NULL} it is not reflexive and therefore partial order relation  does not holds.

R2={(1,1),(2,2) (3,3)} it is reflexive as it has diagonal pairs such as (a,a)

It is antii-symmetric. Also it is  transitive if it has only diagonal elements. 

Therefore the relation is in partial order

R3={(1,1),(2,2) (3,3)(2,1)} It is reflexive as it has all diagonal elements

It is anti symmetric as there exist only (2,1) and not (1,2) in R3. There the relation is in 

Partial order

 

R4={(1,1),(1,3),(2,1)(3,1)} It does not has all diagonal elements ref to table above, hence it does not have reflexive property and therefore partial order does not holds for this relation

R5={(1,1),(2,2),(3,3),(1,2)(1,3)(2,1)(3,1)} It is reflexive as it has all diagonal elements ref table

It is symmetric as we have (1,2) and (2,1). Also we have (1,3) and (3,1). Therefore it is not anti symmetric

 

It is transitive as if we take (1,1) (3,3) then we have (3,1) as in (a,b) and (b,c) we have (a,c) for it to become transitive. Hence the relation is not in partial order 

R6={(1,1),(1,2),(2,1),(2,3),(3,1)(3,2),(3,3)} It is not reflexive as we do not have all diagonal elements ref table above and you will find (2,2) is missing.Therefore relation is not set to be in partial order.

 

Sunday, November 3, 2019

Quiz for score improvement

Pick relevant quiz as per your grade
Note: Sign up/Sign in  is not necessary to run the quiz, you can opt for skip for now. Also choose solo practice option. Happy quizzing :)

1) Congruent triangles( Grade 7)
https://quizizz.com/admin/quiz/58308ebe37a4ff9236d1ca82

2) Comparing quantities
https://quizizz.com/admin/quiz/578c78fc1586ece673f76dcc

3) Matrices(University Grade)
https://quizizz.com/admin/quiz/59c95573a1a3171000119052

4) Sets(K12, University)
https://quizizz.com/admin/quiz/5cc13d00ab784b001b1c1511