# Discrete Math

• Nov 6th 2007, 09:29 AM
MS BATOOL
Discrete Math
:confused: Relation as a set of Pairs http://www.mathhelpforum.com/math-he...cons/icon5.gif
Hi,

Can you help in solving this: -

Let X = {1,2,3,4} and R = {(x,y)|x>y}

Write the relation as a set of order pairs. Then find the inverse of relation. Also draw the directed graph of R.
• Nov 6th 2007, 09:38 AM
Jhevon
Quote:

Originally Posted by MS BATOOL
:confused: Relation as a set of Pairs http://www.mathhelpforum.com/math-he...cons/icon5.gif
Hi,

Can you help in solving this: -

Let X = {1,2,3,4} and R = {(x,y)|x>y}

Write the relation as a set of order pairs. Then find the inverse of relation. Also draw the directed graph of R.

just write out all possible pairs where the first element is greater than the second

so the relation is: R = {(4,3), (4,2), (4,1), (3,2), (3,1), (2,1)}

for the inverse relation, just switch the first and second element in each pair of the original relation

i can't help you with the directed graph, never learnt about that (i would think you just plot the points on the xy-plane and connect them with straight lines, but it might not be that intuitive)
• Nov 6th 2007, 10:25 AM
MS BATOOL
Quote:

Originally Posted by Jhevon
just write out all possible pairs where the first element is greater than the second

so the relation is: R = {(4,3), (4,2), (4,1), (3,2), (3,1), (2,1)}

for the inverse relation, just switch the first and second element in each pair of the original relation

i can't help you with the directed graph, never learnt about that (i would think you just plot the points on the xy-plane and connect them with straight lines, but it might not be that intuitive)

thanks a lot......i was almost near the answer.......but you solve a big problem of mine
• Nov 6th 2007, 10:31 AM
Jhevon
Quote:

Originally Posted by MS BATOOL
thanks a lot......i was almost near the answer.......but you solve a big problem of mine

glad to be of assistance. sorry i couldn't help more. i never did much on relations in this setting
• Nov 6th 2007, 09:46 PM
cu4mail
regarding directed graph, just place 4, 3, 2, 1 elements in differnet locaion and then point them to eachother according to the pairs.. show the arrow on lines as directed from x to y

I hope you understand it now..
• Nov 7th 2007, 08:47 AM
MS BATOOL
Quote:

Originally Posted by cu4mail
regarding directed graph, just place 4, 3, 2, 1 elements in differnet locaion and then point them to eachother according to the pairs.. show the arrow on lines as directed from x to y

I hope you understand it now..

i want to thank you for your care.......i have understood it......thanks again.:)
• Nov 8th 2007, 10:59 AM
mentalcalculation
www.yusnierviera.com
Yusnier Viera can help you, visit his videos at Yusnier Viera: Video Gallery and you'll see or you can join to his forum at www.yusnierviera.com'forum.aspx
Good Luck.
• Nov 8th 2007, 11:07 AM
MS BATOOL
Thanks
Quote:

Originally Posted by mentalcalculation
Yusnier Viera can help you, visit his videos at Yusnier Viera: Video Gallery and you'll see or you can join to his forum at www.yusnierviera.com'forum.aspx
Good Luck.

Dear mentalcalculation, i hope you will be fine....i just want to thanks for your care.....also want to welcome you in mathhelpforum.......thanks again(Handshake)