j ) are constant cu u du o ng th an Given these data, the statement setqueen is refined as: x[i]:=j; a[j]:=false; b[i+j]:=false;c[i-j]:=false; The statement removequeen is refined as: a[j] = true; b[i+j] = true ; c[i-j] := true The condition safe is represented as: a[j] ∧ b[i+j] ∧ c[i-j] 18 CuuDuongThanCong.com https://fb.com/tailieudientucntt u=x+y 16 c om y ng an co th ng du o cu u x -7 CuuDuongThanCong.com -3 v=x-y https://fb.com/tailieudientucntt 19 cu u du o an co ng c om begin x[i]:=j; a[j]:=false; b[i+j]:=false; c[i-j]:=false; if i