4) (12 points) 5 brothers are logged in an online game. Clearly justify whether it is possible to determine who is currently playing based on the following: If Ahmad is playing online, so is Ridhwan. Faizan and Kamal are either both playing online, or neither of them is. Either Kamal or Hisham, or both are playing online. Either Ridhwan or Faizan, but not both, are playing online. If Hisham is playing online, then so are Ahmad and Kamal. 5) (12 points) Recall inhabitants of the island of knights and knaves created by Smullyan, where knights always tell the truth and knaves always lie. You encounter three people, A, B and C. A claims, I am a knight or B is a knave. B tells you, A is a knight and C is a knave. C says, I and B are different. Can you determine who is knight and who is knave? Justify your answer. 6) (12 points) Construct a combinatorial circuit using inverters, OR gates, and AND gates that produces the output (( -pvr)19) V(-p V (qar)) from input bits p, q, and r