Epigraph
# Definition
Suppose $X$ is a Set, $(Y, \leq)$ is a Partial Ordering, $f: X \to Y$. The Epigraph of $f$ is the Set $$\text{Epi}(f) = {(x, y) \in X \times Y : y \geq f(x)}$$
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Suppose $X$ is a Set, $(Y, \leq)$ is a Partial Ordering, $f: X \to Y$. The Epigraph of $f$ is the Set $$\text{Epi}(f) = {(x, y) \in X \times Y : y \geq f(x)}$$