A very special island is inhabited only by knights and knaves. Knights always tell the truth, and knaves always lie. You meet 6 inhabitants: Emily, Matthew, Evelyn, Zoey, Abigail, and Aria. Emily stated, "Zoey is a knight and Abigail is a knave". Matthew asserted: "If Evelyn is a knave then Matthew is a knight". Evelyn was heard saying, "If Emily is a knight then Abigail is a knave". Zoey asserted: "Aria is a knight or Emily is a knave". As Abigail put it, "Evelyn is not a knight". In Aria's words: "Matthew is not a knave". So who is a knight and who is a knave?
Emily is a knight, Matthew is a knight, Evelyn is a knight, Zoey is a knight, Abigail is a knave, and Aria is a knight.
(1) Emily is a knight
(2) Matthew is a knight
(3) Evelyn is a knight
(4) Zoey is a knight
(5) Abigail is a knave
(6) Aria is a knight
Assume Emily is a knight. No contradiction is found in their claim that Zoey is a knight and Abigail is a knave. Assume Zoey is a knight. No contradiction is found in their claim that Aria is a knight or Emily is a knave. Assume Aria is a knight. No contradiction is found in their claim that Matthew is not a knave. Assume Matthew is a knight. No contradiction is found in their claim that If Evelyn is a knave then Matthew is a knight. Assume Evelyn is a knight. No contradiction is found in their claim that If Emily is a knight then Abigail is a knave. Abigail cannot be a knight, because this would contradict the claim of Emily that Zoey is a knight and Abigail is a knave. Assume Abigail is a knave. No contradiction is found in their false claim that Evelyn is not a knight.