The transitive closure of the relation R={(1,3),(5,5),(1,6),(3,3),(5,6)} is the smallest transitive relation that contains R. Since for relation R we have that (a,b)∈R and (b,c)∈R imply (a,c)∈R for all pairs that belong to R, we conclude that R is transitive, and hence its transitive closure is equal to R.
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