Consider the following premises. If John were a musician, then Robert is playing a game. If Jessica were a sailor, then Robert is not playing a game. If Mary plays squash, then Robert is playing a game. John is a musician or Mary is playing squash. Can we infer the following from them? Jessica is a sailor.
 From the fact that if John were a musician, then Robert is playing a game, that if Mary plays squash, then Robert is playing a game, and that John is a musician or Mary is playing squash we can infer that Robert is playing a game. Finally, from the fact that if Jessica were a sailor, then Robert is not playing a game, and that Robert is playing a game we can infer that Jessica is not a sailor, which contradicts that Jessica is a sailor. Therefore, the answer is no.