functions.tex

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    \noindent
	\begin{tabular}{cccc}
	$\{a, b, c, d\} \to \{1,2,3\}$: & $\{a, b, c\} \to \{1,2,3\}$: & \{all people\}$ \to \mathbb{N}$: & \{Czech citizens\} $\to \mathbb{N}$: \\
	$(a,1), (b, 1), (c, 2), (d,3)$ & $(a,1), (b, 1), (c, 2), (c, 3)$ & (person, their height) & (person, their national ID)\\
	&&&\\
	$\mathbb{Z} \to \mathbb{Z}$: & $\mathbb{R} \to \mathbb{R}$: & $\mathbb{Z} \to \mathbb{Z}$: & $\mathbb{R} \to \mathbb{R}$:  \\
	$f(x) = x + 7$ & $f(x) = x + 7$ & $f(x) = 3x + 1$ & $f(x) = 3x + 1$\\

	&&&\\
	$\mathbb{Z} \to \mathbb{Z}$: & $\mathbb{R} \to \mathbb{R}$: & $\mathbb{Z} \to \mathbb{Z}$: & $\mathbb{R} \to \mathbb{R}$:  \\
	$f(x) = x^2 + x + 1$ & $f(x) = x^2 + x + 1$ & $f(x) = \tan(x)$ & $f(x) = \tan(x)$ \\
	&&&\\
	\end{tabular}

	\begin{tabular}{ccc}
	\{students of this course\} $\to$ \{their grades\}: & \{all people\} $\to$ \{all people\}: & $\mathbb{N} \to \mathbb{N}$:\\
	(student, their grade) & \{(a, b)$\mid$ $a$ a $b$ are twins\} & $\{(a, b)\mid b=a+1 \}$\\
	&&\\
	\end{tabular}
	
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}


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