The 1st set has 5 different values of +y+ for +x+=+1+ and violates definition -------------- The 2nd set is a function ----------------------- The 3rd set has
( 1,2 ) & ( 1,1 ) ( 2,3 ) & ( 2,2 ) ( 3,4 ) & ( 3,3 ) Each of these pairs violates the definition ---------------- The 4th set has ( 2,-7 ) & ( 2,0 ) which violate definition
