15. (6 points) (a) A hospital maintains a set of Patients, P, who have ever heen admitted to the hospital at some time. (No patient is ever deleted from this set, even after they leave the hospital.) There is also a set Beds, B, describing the beds available for patients. Consider the function currentBed that maps Patients to Beds. The function relates a patient to the bed that he/she is curreutly oceupying in the hospital. (a) Is this function total? (b) Is the function one-to-one? (c) Is the function onto? Explain your answers (b) Let Dates be a set of dates. Consider the function date 1stAdmitted that maps Patients to Dates, relating a patient to the date he/she was first adnitted to the hospital. (a) Is this function total? (b) Is the function one-to-one? (e) Is the function onto? Explain your answers