A proposition derived by negating and permuting the terms of another,equivalent proposition,for example,All not-Y is not-X is the contrapositive of All X is Y. 质位变换命题，由否定和置换另一等价命题的项而得到的命题；例如，“所有的非Y是非X”是“所有的X是Y”的质位变换命题。
A proposition derived by negating and permuting the terms of another, equivalent proposition;for example, All not - Y is not - X is the contrapositive of All X is Y. 质位变换命题由否定和置换另一等价命题的项而得到的命题；例如，“所有的非y是非X”是“所有的X是y”的质位变换命题
A proposition derived by negating and permuting the terms of another, equivalent proposition;for example, All not - Y is not - X is the contrapositive of All X is Y . 质位变换命题由否定和置换另一等价命题的项而得到的命题；例如，“所有的非y是非X”是“所有的X是y”的质位变换命题
A proposition derived by negating and permuting the terms of another,equivalent proposition;for example,All not - Y is not - X is the contrapositive of All X is Y. 质位变换命题由否定和置换另一等价命题的项而得到的命题；例如，“所有的非Y是非X”是“所有的X是Y”的质位变换命题
A proposition derived by negating and permuting the terms of another, equivalent proposition; for example, All not-Y is not-X is the contrapositive of All X is Y. 质位变换命题由否定和置换另一等价命题的项而得到的命题；例如，“所有的非y是非x”是“所有的x是y”的质位变换命题
