Problem 4. (20 points, at 5 each) Let s denote Yida studies; t denote "Steve studies; p denote Yida passes the class; . q denote "Steve passes the class. Write propositional formulas for the following propositions: a) Yida studies but Steve does not. Submit a file named p4a.py b) Steve passes the class only if he studies. Submit a file named p4p.py c) Neither Yida nor Steve passes the class. Submit a file named p4c.py d) Both Yida and Steve pass the class but only one of them studies. Submit a file named p4d.py