27. Prove that the binary relation on sets defined by X- Y if, and only if, card(CX) card (Y) is an equivalence relation. 28. Prove the Schrder-Bernstein Theorem. 29. Give a recursive definition of the relation is equal to on N N using the operator s 30. Give a recursive definition of the relation greater than on N x N using the successor 31. Give a recursive definition of the set of points [m, n] that lie on the line n 3m in 32. Give a recursive definition of the set of points [m, n] that lie on or under the line n 3m 33) Give a recursive definition of the operation of multiplication of natural numbers using 34. Give a recursive definition of the predecessor operation operator s. N x N. Use s as the operator in the definition. in N x N. Use s as the operator in the definition. the operations s and addition. pred(n)n-1 otherwise