Saturday, March 2, 2013

Draft

Version of 2018-12-05 or later

Draft Outline

The basic building block for Boolean geometry and logic
is the Boolean “object of truth values”: $\bftwo = \{\ladjbot,\radjtop\} = \{\text{false},\text{true}\}$.
We give this set the (linear) order $\ladjbot\lt\radjtop$, in accordance with the ex falso sequitur quodlibet principle of logic.

Boolean geometry then considers powers of $\bftwo$:
the Boolean point $\bftwo^0 \cong 1$ ,
the Boolean line $\bftwo^1 \cong \bftwo$ ,
the Boolean plane $\bftwo^2 \cong \bftwo\times\bftwo$ ,
the Boolean cube $\bftwo^3\cong \bftwo\times\bftwo\times\bftwo$ , and so on.

The next step is to consider Boolean (i.e., $\bftwo$-valued) functions (which we will call predicates) defined on these geometric objects.
Since (the Boolean object of truth values, $\bftwo$) is (the subobject classifier) for (the category of sets),
such predicates are in bijection with
the subsets of (the source (domain) of the predicate).


A comparison of the traditional way of presenting truth tables to
the geometrical way (the graph of the function from $\bftwo\times\bftwo$ to $\bftwo$ determined by the truth table):
Truth table for $\objA\wedge\objB$
$\objA$ $\objB$ $\objA\wedge\objB$
$\radjtop$ $\radjtop$ $\radjtop$
$\ladjbot$ $\radjtop$ $\ladjbot$
$\radjtop$ $\ladjbot$ $\ladjbot$
$\ladjbot$ $\ladjbot$ $\ladjbot$
The graph of the function $\wedge : \bftwo\times\bftwo \rightarrow \bftwo$
$\objB$
$\radjtop$ $\ladjbot$ $\Rule{64px}{2px}{0px}$ $\radjtop$
$\neg\objA$ $\Rule{2px}{32px}{32px}$ $\objA\wedge\objB$ $\Rule{2px}{32px}{32px}$ $\objA$
$\ladjbot$ $\ladjbot$ $\Rule{64px}{2px}{0px}$ $\ladjbot$
$\ladjbot$ $\neg\objB$ $\radjtop$

$\objB\in\{\ladjbot,\radjtop\}$
$\vary\in\{0,1\}$
$\Big\uparrow$ $\objB$
$1$ $\top$ $\begin{array}{c}\langle \ladjbot, \radjtop \rangle\\\objB - \objA\\\end{array}$ $\Rule{64px}{2px}{0px}$ $\begin{array}{c}\langle \radjtop, \radjtop \rangle\\\objA\cap\objB\\\end{array}$
$\neg\objA$ $\Rule{2px}{32px}{32px}$ $\Rule{2px}{32px}{32px}$ $\objA$
$0$ $\bot$ $\begin{array}{c}\langle \ladjbot, \ladjbot \rangle\\\end{array}$ $\Rule{64px}{2px}{0px}$ $\begin{array}{c}\langle \radjtop, \ladjbot \rangle\\\objA - \objB\\\end{array}$ $\longrightarrow \objA\in\{\ladjbot,\radjtop\}, \varx\in\{0,1\}$
$\bot$ $\neg\objB$ $\top$
$0$ $1$

${2\times2 \choose 4} = 1$ all
$\objB$
$\radjtop$ $\radjtop$ $\Rule{64px}{2px}{0px}$ $\radjtop$
$\neg\objA$ $\Rule{2px}{32px}{32px}$ $\begin{array}{c}\radjtop\\1\end{array}$ $\Rule{2px}{32px}{32px}$ $\objA$
$\ladjbot$ $\radjtop$ $\Rule{64px}{2px}{0px}$ $\radjtop$
$\ladjbot$ $\neg\objB$ $\radjtop$
${2\times2 \choose 3} = 4$ ells
angles
$\objB$
$\radjtop$ $\radjtop$ $\Rule{128px}{2px}{0px}$ $\radjtop$
$\neg\objA$ $\Rule{2px}{32px}{32px}$ $\begin{array}{c}\objA\vee\objB\\(\varx+1)(\vary+1)+1\\\varx\vary+\varx+\vary\end{array}$ $\Rule{2px}{32px}{32px}$ $\objA$
$\ladjbot$ $\ladjbot$ $\Rule{128px}{2px}{0px}$ $\radjtop$
$\ladjbot$ $\neg\objB$ $\radjtop$
$\objB$
$\radjtop$ $\radjtop$ $\Rule{96px}{2px}{0px}$ $\radjtop$
$\neg\objA$ $\Rule{2px}{32px}{32px}$ $\begin{array}{c}\neg\objA\vee\objB\\\objA\Rightarrow\objB\\\neg(\objA\wedge\neg\objB)\\\varx(\vary+1)+1\\\varx\vary+\varx+1\end{array}$ $\Rule{2px}{32px}{32px}$ $\objA$
$\ladjbot$ $\radjtop$ $\Rule{96px}{2px}{0px}$ $\ladjbot$
$\ladjbot$ $\neg\objB$ $\radjtop$
$\objB$
$\radjtop$ $\ladjbot$ $\Rule{96px}{2px}{0px}$ $\radjtop$
$\neg\objA$ $\Rule{2px}{32px}{32px}$ $\begin{array}{c}\objA\vee\neg\objB\\\objA\Leftarrow\objB\\\neg(\neg\objA\wedge\objB)\\(\varx+1)\vary+1\\\varx\vary+\vary+1\end{array}$ $\Rule{2px}{32px}{32px}$ $\objA$
$\ladjbot$ $\radjtop$ $\Rule{96px}{2px}{0px}$ $\radjtop$
$\ladjbot$ $\neg\objB$ $\radjtop$
$\objB$
$\radjtop$ $\radjtop$ $\Rule{128px}{2px}{0px}$ $\ladjbot$
$\neg\objA$ $\Rule{2px}{32px}{32px}$ $\begin{array}{c}\neg\objA\vee\neg\objB\\\neg(\objA\wedge\objB)\\\varx\vary+1\end{array}$ $\Rule{2px}{32px}{32px}$ $\objA$
$\ladjbot$ $\radjtop$ $\Rule{128px}{2px}{0px}$ $\radjtop$
$\ladjbot$ $\neg\objB$ $\radjtop$
${2\times2 \choose 2} = 6$ lines
$\objB$
$\radjtop$ $\ladjbot$ $\Rule{64px}{2px}{0px}$ $\radjtop$
$\neg\objA$ $\Rule{2px}{32px}{32px}$ $\begin{array}{c}\objA\\\varx\end{array}$ $\Rule{2px}{32px}{32px}$ $\objA$
$\ladjbot$ $\ladjbot$ $\Rule{64px}{2px}{0px}$ $\radjtop$
$\ladjbot$ $\neg\objB$ $\radjtop$
$\objB$
$\radjtop$ $\radjtop$ $\Rule{128px}{2px}{0px}$ $\radjtop$
$\neg\objA$ $\Rule{2px}{32px}{32px}$ $\begin{array}{c}\objB\\\vary\end{array}$ $\Rule{2px}{32px}{32px}$ $\objA$
$\ladjbot$ $\ladjbot$ $\Rule{128px}{2px}{0px}$ $\ladjbot$
$\ladjbot$ $\neg\objB$ $\radjtop$
$\objB$
$\radjtop$ $\ladjbot$ $\Rule{96px}{2px}{0px}$ $\radjtop$
$\neg\objA$ $\Rule{2px}{32px}{32px}$ $\begin{array}{c}\objA\Leftrightarrow\objB\\\varx+\vary+1\end{array}$ $\Rule{2px}{32px}{32px}$ $\objA$
$\ladjbot$ $\radjtop$ $\Rule{96px}{2px}{0px}$ $\ladjbot$
$\ladjbot$ $\neg\objB$ $\radjtop$
$\objB$
$\radjtop$ $\radjtop$ $\Rule{96px}{2px}{0px}$ $\ladjbot$
$\neg\objA$ $\Rule{2px}{32px}{32px}$ $\begin{array}{c}\objA \veebar\objB\\\varx+\vary\end{array}$ $\Rule{2px}{32px}{32px}$ $\objA$
$\ladjbot$ $\ladjbot$ $\Rule{96px}{2px}{0px}$ $\radjtop$
$\ladjbot$ $\neg\objB$ $\radjtop$
$\objB$
$\radjtop$ $\ladjbot$ $\Rule{128px}{2px}{0px}$ $\ladjbot$
$\neg\objA$ $\Rule{2px}{32px}{32px}$ $\begin{array}{c}\neg\objB\\\vary+1\end{array}$ $\Rule{2px}{32px}{32px}$ $\objA$
$\ladjbot$ $\radjtop$ $\Rule{128px}{2px}{0px}$ $\radjtop$
$\ladjbot$ $\neg\objB$ $\radjtop$
$\objB$
$\radjtop$ $\radjtop$ $\Rule{64px}{2px}{0px}$ $\ladjbot$
$\neg\objA$ $\Rule{2px}{32px}{32px}$ $\begin{array}{c}\neg\objA\\\varx+1\end{array}$ $\Rule{2px}{32px}{32px}$ $\objA$
$\ladjbot$ $\radjtop$ $\Rule{64px}{2px}{0px}$ $\ladjbot$
$\ladjbot$ $\neg\objB$ $\radjtop$
${2\times2 \choose 1} = 4$ points
vertices
$\objB$
$\radjtop$ $\ladjbot$ $\Rule{128px}{2px}{0px}$ $\radjtop$
$\neg\objA$ $\Rule{2px}{32px}{32px}$ $\begin{array}{c}\objA\wedge\objB\\\varx\vary\end{array}$ $\Rule{2px}{32px}{32px}$ $\objA$
$\ladjbot$ $\ladjbot$ $\Rule{128px}{2px}{0px}$ $\ladjbot$
$\ladjbot$ $\neg\objB$ $\radjtop$
$\objB$
$\radjtop$ $\radjtop$ $\Rule{96px}{2px}{0px}$ $\ladjbot$
$\neg\objA$ $\Rule{2px}{32px}{32px}$ $\begin{array}{c}\neg\objA\wedge\objB\\(\varx+1)\vary\\\varx\vary+\vary\end{array}$ $\Rule{2px}{32px}{32px}$ $\objA$
$\ladjbot$ $\ladjbot$ $\Rule{96px}{2px}{0px}$ $\ladjbot$
$\ladjbot$ $\neg\objB$ $\radjtop$
$\objB$
$\radjtop$ $\ladjbot$ $\Rule{96px}{2px}{0px}$ $\ladjbot$
$\neg\objA$ $\Rule{2px}{32px}{32px}$ $\begin{array}{c}\objA\wedge\neg\objB\\\varx(\vary+1)\\\varx\vary+\varx\end{array}$ $\Rule{2px}{32px}{32px}$ $\objA$
$\ladjbot$ $\ladjbot$ $\Rule{96px}{2px}{0px}$ $\radjtop$
$\ladjbot$ $\neg\objB$ $\radjtop$
$\objB$
$\radjtop$ $\ladjbot$ $\Rule{128px}{2px}{0px}$ $\ladjbot$
$\neg\objA$ $\Rule{2px}{32px}{32px}$ $\begin{array}{c}\neg\objA\wedge\neg\objB\\(\varx+1)(\vary+1)\\\varx\vary+\varx+\vary+1\end{array}$ $\Rule{2px}{32px}{32px}$ $\objA$
$\ladjbot$ $\radjtop$ $\Rule{128px}{2px}{0px}$ $\ladjbot$
$\ladjbot$ $\neg\objB$ $\radjtop$
${2\times2 \choose 0} = 1$ none
$\objB$
$\radjtop$ $\ladjbot$ $\Rule{64px}{2px}{0px}$ $\ladjbot$
$\neg\objA$ $\Rule{2px}{32px}{32px}$ $\begin{array}{c}\ladjbot\\0\end{array}$ $\Rule{2px}{32px}{32px}$ $\objA$
$\ladjbot$ $\ladjbot$ $\Rule{64px}{2px}{0px}$ $\ladjbot$
$\ladjbot$ $\neg\objB$ $\radjtop$

\[\begin{array}{} &&& dot & \unicode{0x2500} & dot \\ && \unicode{0x2571} && \unicode{0x2571} \\ & dot & \unicode{0x2500} & dot \\ \\ && dot & \unicode{0x2500} & dot \\ & \unicode{0x2571} && \unicode{0x2571} \\ dot & \unicode{0x2500} & dot \\ \end{array}\]

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