17. Another solution for #7 would be to create a "one-set-diagram since the relation is on a single set, ie A. Redraw the above relation using a single set. 18.Arrows in an arrow diagram can have two heads, meaning that the relationship goes both ways. For example the relation R: Domain & Codomain: the set A (1, 2, 3, 4, 5, 6) Rule: (x, y) is in R if x-y is an even integer Draw a one-set diagram for this relation using a double-headed arrow to indicate of the relation applies both directions