QUESTION $6$

$[6]$

You are given the sentence

AAxAAy$((R(x,y)vvR(y,x))$not$(R(x,y{)}^{{?}^{?}}R(y,x)))$

where $R$ is a predicate with two arguments.

Question $6\mathrm{.}1$

Show that the sentence is satisfiable. In other words: Construct either a mathematical or a non mathematical model where the sentence is true.

Question $6\mathrm{.}2$

Show that the sentence is not valid. In other words: Construct either a mathematical or a non mathematical model where the sentence is false.