# Thread: binary relations 4 parts to this question second one . adjacency matrix

1. ## binary relations 4 parts to this question second one . adjacency matrix

Let S = {0,1,2,3,4} Let R be the binary relation on S such that aRb if and only if a+b=3 and a ≤ 3.
(a) Write this relation down as a subset of the Cartesian product S x S.

The answer to this was :

R = {0,3}{1,2}{2,1}{3,0}

.....0..1..2..3
0...0..0..0..1
1...0..0..1..0
2...0..1..0..0
3..1...0..0..0

This adjacency Matrix is correct ?

2. ## Re: binary relations 4 parts to this question second one . adjacency matrix

Originally Posted by bee77
Let S = {0,1,2,3,4} Let R be the binary relation on S such that aRb if and only if a+b=3 and a ≤ 3.
(a) Write this relation down as a subset of the Cartesian product S x S.
The answer to this was :R = {0,3}{1,2}{2,1}{3,0}
.....0..1..2..3
0...0..0..0..1
1...0..0..1..0
2...0..1..0..0
3..1...0..0..0
This adjacency Matrix is correct ?
I should think this more like it:
$\begin{array}{*{20}{c}} R&|&0&1&2&3&4 \\ \hline 0&|&0&0&0&1&0 \\ 1&|&0&0&1&0&0 \\ 2&|&0&1&0&0&0 \\ 3&|&1&0&0&0&0 \\ 4&|&0&0&0&0&0 \end{array}$

3. ## Re: binary relations 4 parts to this question second one . adjacency matrix

ahhh thanks Plato ,missed the 4 relations thanks ..