logical operators - Quine's notation in Three Grades of Modal Involvement

Question

I am not familiar with Quine's notation and am very puzzled by it. Does anyone know how these notations should be interpreted? In particular, what x hat and lambda stand for?

From Quine's Three Grades of Modal Involvement

question from:https://stackoverflow.com/questions/66051831/quines-notation-in-three-grades-of-modal-involvement

Answer 1

Waitting for answers