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text: 'In mathematics, the notation $f : X \\to Y$ (here, "colon-to notation," because the arrow $\\to$ is written "\\to" in [LaTeX]) means that $f$ is a [3jy function] with [3js domain] $X$ and [3lg codomain] $Y$. It can be read "$f$, a function from $X$ to $Y$." \n\nThis can be thought of as ascribing a function type to the value $f$. The use of a colon to express that a given value has a given type, as is done in type theory, is a generalization of this notation.\n\n# Examples\n\n$f : \\mathbb{R} \\to \\mathbb{R}$ means that $f$ is a function from the real numbers to the real numbers, such as $x \\mapsto x^2$ ([3vm mapsto notation]). \n\n$f : \\mathbb{R} \\times \\mathbb{R} \\to \\mathbb{R}$ means that $f$ is a function from pairs of real numbers to real numbers. The $\\times$ here refers to the [3xb Cartesian product] of [3jz sets]. ',
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