If q cannot be deduced from p, it is said that p is an insufficient condition of q and q is an unnecessary condition of p.
If Q can be deduced from P and Q can't, then P is a necessary and sufficient condition for Q, and Q is a necessary and sufficient condition for P. 。
If neither Q nor Q can be deduced from P, it is said that P is neither sufficient nor necessary for Q, and Q is neither sufficient nor necessary for P. 。
If q can be deduced from p and q can be deduced from p, it is said that p is a necessary and sufficient condition for q, and q is a necessary and sufficient condition for p.