Quantifiers

Example: Consider the statement:

$\exists m \in \mathbb{Z}, m^2 = 25$.

This means "there exists an integer $m$ such that $m^2 = 25$."

This is true since $x = 5$ and $x = -5$ satisfy the equation.

Because the statement uses a $\exists$ quantifier, it is actually enough just to point at one such integer, e.g., $x = 5$, to prove the correctness of this statement.

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Fun fact: note that $\forall$ is an upside-down letter A (reminiscent of the word 'all') and that $\exists$ is a flipped letter E (reminiscent of the word 'exists').