added alternative solution

pr7.cql

+.in
+F:3,
+G:3
+
+.out
+F x G;
+filter (\(r) -> not(isEmpty(r[2])) and not(isEmpty(r[3])) and [r[2], r[3]] == [r[4], r[5]]);
+#alternatively: filter (\(r) -> not(isEmpty(r[2])) and not(isEmpty(r[3])) and r[2]==r[4] and r[3]==r[5]);
+map (\(r) -> r[1,6]);
\ No newline at end of file