请教一道离散数学题Find a common universe for variables x, y, z, w for which the statement∀x∀y∀z∃w ((w≠x)∧(w≠ y)∧(w≠z))is true and another common universe for these variables in which it isfalse.
问题描述：
请教一道离散数学题
Find a common universe for variables x, y, z, w for which the statement
∀x∀y∀z∃w ((w≠x)∧(w≠ y)∧(w≠z))
is true and another common universe for these variables in which it is
false.
答
When the common universe is R,the statement is true.
When the common universe is {1,2,3},it is false.