Denial of Universality/Examples/x less than or equal to 3/Examples/0 to 3

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Example of Denial of Universality: $\forall x \in S: x \le 3$

Let $P$ be the statement:

$\forall x \in S: x \le 3$

and $\lnot P$ its negation:

$\exists x \in S: x > 3$

Let $S = \closedint 0 3$ where $\closedint \cdot \cdot$ denotes a closed real interval.

Then we have that:

$P$ is true

and consequently:

$\lnot P$ is false


By definition of closed real interval:

$\forall x \in S: 0 \le x \le 3$

and so:

$\forall x \in S: x \le 3$

Hence its negation is false.