if and only if

g
gokgs
楼主 (北美华人网)

A number ends with 5 only if it is divisible by 5.
谁能讲明白? 哈哈
f
fridec2
回复 1楼gokgs的帖子
哈哈,研究数理逻辑吗?
statement-X:A number ends with 5 statement-Y:it is divisible by 5
“A number ends with 5 only if it is divisible by 5“ 等价于:If statement-X is True, then statement-Y is True