A very special island is inhabited only by knights and knaves. Knights always tell the truth, and knaves always lie. You meet 6 inhabitants: Henry, Riley, Victoria, Avery, Sofia, and William. In Henry's words: "William is a knight if and only if Avery is a knight". Riley asserted: "Victoria is not a knave". "Sofia is a knave or Henry is a knight," Victoria mentioned. Avery told you that Victoria is a knight and Henry is a knight. "Riley is a knight or William is a knave," Sofia declared. In William's words: "Avery is a knave or Avery is a knight". So who is a knight and who is a knave?
Henry is a knight, Riley is a knight, Victoria is a knight, Avery is a knight, Sofia is a knight, and William is a knight.
(1) Henry is a knight
(2) Riley is a knight
(3) Victoria is a knight
(4) Avery is a knight
(5) Sofia is a knight
(6) William is a knight
Assume Henry is a knight. No contradiction is found in their claim that William is a knight if and only if Avery is a knight. Assume William is a knight. No contradiction is found in their claim that Avery is a knave or Avery is a knight. Assume Avery is a knight. No contradiction is found in their claim that Victoria is a knight and Henry is a knight. Assume Victoria is a knight. No contradiction is found in their claim that Sofia is a knave or Henry is a knight. Assume Sofia is a knight. No contradiction is found in their claim that Riley is a knight or William is a knave. Assume Riley is a knight. No contradiction is found in their claim that Victoria is not a knave.