If 'A & B' means 'A is the father of B' and 'A @ B' means 'A is the sister of B', then which of the following expressions means 'H is the father of M'?

H & K means H is father of K, K @ P means K is sister of P, P @ M means P is sister of M — so H is father of K who is sister of P who is sister of M, meaning H is grandfather, not father of M. Re-reading: H & K @ P @ M: H is father of K, K is sister of P, P is sister of M, so H is father of M through the sibling chain. This correctly establishes H as the father of M.