A very special island is inhabited only by knights and knaves. Knights always tell the truth, and knaves always lie. You meet 6 inhabitants: Grace, Charlotte, Jack, Sebastian, Abigail, and Mia. In a statement by Grace: "If Jack is a knave then Abigail is a knave". "Sebastian is not a knave," Charlotte mentioned. Jack noted, "Mia is a knight". Sebastian said that Abigail is a knight if and only if Grace is a knight. Abigail commented, "Charlotte is a knave or Charlotte is a knight". According to Mia, "Abigail is a knight or Grace is a knight". So who is a knight and who is a knave?
Grace is a knight, Charlotte is a knight, Jack is a knight, Sebastian is a knight, Abigail is a knight, and Mia is a knight.
(1) Grace is a knight
(2) Charlotte is a knight
(3) Jack is a knight
(4) Sebastian is a knight
(5) Abigail is a knight
(6) Mia is a knight
Assume Grace is a knight. No contradiction is found in their claim that If Jack is a knave then Abigail is a knave. Assume Jack is a knight. No contradiction is found in their claim that Mia is a knight. Assume Mia is a knight. No contradiction is found in their claim that Abigail is a knight or Grace is a knight. Assume Abigail is a knight. No contradiction is found in their claim that Charlotte is a knave or Charlotte is a knight. Assume Charlotte is a knight. No contradiction is found in their claim that Sebastian is not a knave. Assume Sebastian is a knight. No contradiction is found in their claim that Abigail is a knight if and only if Grace is a knight.