# Thread: arrow diagram part 3 of the question

1. ## arrow diagram part 3 of the question

so I must draw an arrow diagram
of the S = {0,1,2,3,4}
R = {0,3}{1,2}{2,1}{3,0}

Do the 4's need to be there ? Thanks

2. ## Re: arrow diagram part 3 of the question

Originally Posted by bee77
so I must draw an arrow diagram
of the S = {0,1,2,3,4}
R = {0,3}{1,2}{2,1}{3,0}

Do the 4's need to be there ? Thanks
It depends on what you are trying to have your arrow diagram represent. If you want to show that the relation R on S does not include (4,s) or (s,4) for any $s\in S$, then, it does need 4. If you are trying for a minimalistic representation where you only want to show the existing pairings, then the 4 could be omitted. The latter could, potentially, be misinterpreted as being an arrow diagram for a relation $R'$ on the set $S' = \{0,1,2,3\}$, so to make sure that your relation is properly interpreted, it may be better to keep the 4, even though it is not "used" by $R$.

3. ## Re: arrow diagram part 3 of the question

Thanks Slip Eternal
I'll take in what you said
cheers