View source for Directory talk:Jon Awbrey/Papers/Differential Propositional Calculus

=Current Version @ PlanetMath : TeX Format=

<pre>
A \textbf{differential propositional calculus} is a \PMlinkname{propositional calculus}{PropositionalCalculus} extended by a set of terms for describing aspects of change and difference, for example, processes that take place in a universe of discourse or transformations that map a source universe into a target universe.

\tableofcontents

\section{Casual introduction}

Consider the situation represented by the venn diagram in Figure 1.

\begin{figure}[h]\begin{centering}
\begin{footnotesize}\begin{verbatim}
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\end{verbatim}\end{footnotesize}
Figure 1.  Local Habitations, And Names
\end{centering}\end{figure}

The area of the rectangle represents a universe of discourse, $X.$  This might be a population of individuals having various additional properties or it might be a collection of locations that various individuals occupy.  The area of the "circle" represents the individuals that have the property $q$ or the locations that fall within the corresponding region $Q.$  Four individuals, $h, i, j, k,$ are singled out by name.  It happens that $i$ and $j$ currently reside in region $Q$ while $h$ and $k$ do not.

Now consider the situation represented by the venn diagram in Figure 2.

\begin{figure}[h]\begin{centering}
\begin{footnotesize}\begin{verbatim}
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\end{verbatim}\end{footnotesize}
Figure 2.  Same Names, Different Habitations
\end{centering}\end{figure}

Figure 2 differs from Figure 1 solely in the circumstance that the object $j$ is outside the region $Q$ while the object $k$ is inside the region $Q.$  So far, there is nothing that says that our encountering these Figures in this order is other than purely accidental, but if we interpret the present sequence of frames as a ``moving picture" representation of their natural order in a temporal process, then it would be natural to say that $h$ and $i$ have remained as they were with regard to quality $q$ while $j$ and $k$ have changed their standings in that respect.  In particular, $j$ has moved from the region where $q$ is $\operatorname{true}$ to the region where $q$ is $\operatorname{false}$ while $k$ has moved from the region where $q$ is $\operatorname{false}$ to the region where $q$ is $\operatorname{true}.$

Figure $1^\prime$ reprises the situation shown in Figure 1, but adduces a new quality for the purpose of explaining what we know --- now --- we'll see in Figure 2.

\begin{figure}[h]\begin{centering}
\begin{footnotesize}\begin{verbatim}
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| . . . | . . . . . Q . . | . . . | . . dQ. . . . . | . . . |
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o-----------------------------------------------------------o
\end{verbatim}\end{footnotesize}
Figure $1^\prime$.  Back, To The Future
\end{centering}\end{figure}

This new quality, $\operatorname{d}q,$ is an example of a \textit{differential quality}, since its absence or presence qualifies the absence or presence of change occurring in another quality.  As with any other quality, it is represented in the venn diagram by means of a ``circle" that distinguishes two halves of the universe of discourse, in this case, outside and inside the region $\operatorname{d}Q.$
</pre>

=Draft Conversion @ MyWikiBiz : Wiki Format=

A '''differential propositional calculus''' is a [[propositional calculus]] extended by a set of terms for describing aspects of change and difference, for example, processes that take place in a [[universe of discourse]] or transformations that map a source universe into a target universe.

==Casual introduction==

Consider the situation represented by the venn diagram in Figure&nbsp;1.

<center><pre>
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| X . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
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o-----------------------------------------------------------o
</pre>
'''Figure 1.  Local Habitations, And Names'''
</center>

The area of the rectangle represents a universe of discourse, <math>X.\!</math>  This might be a population of individuals having various additional properties or it might be a collection of locations that various individuals occupy.  The area of the "circle" represents the individuals that have the property <math>q\!</math> or the locations that fall within the corresponding region <math>Q.\!</math>  Four individuals, <math>h, i, j, k,\!</math> are singled out by name.  It happens that <math>i\!</math> and <math>j\!</math> currently reside in region <math>Q\!</math> while <math>h\!</math> and <math>k\!</math> do not.

Now consider the situation represented by the venn diagram in Figure&nbsp;2.

<center><pre>
o-----------------------------------------------------------o
| X . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
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</pre>
'''Figure 2.  Same Names, Different Habitations'''
</center>

Figure 2 differs from Figure 1 solely in the circumstance that the object <math>j\!</math> is outside the region <math>Q\!</math> while the object <math>k\!</math> is inside the region <math>Q.\!</math>  So far, there is nothing that says that our encountering these Figures in this order is other than purely accidental, but if we interpret the present sequence of frames as a "moving picture" representation of their natural order in a temporal process, then it would be natural to say that <math>h\!</math> and <math>i\!</math> have remained as they were with regard to quality <math>q\!</math> while <math>j\!</math> and <math>k\!</math> have changed their standings in that respect.  In particular, <math>j\!</math> has moved from the region where <math>q\!</math> is <math>\operatorname{true}\!</math> to the region where <math>q\!</math> is <math>\operatorname{false}\!</math> while <math>k\!</math> has moved from the region where <math>q\!</math> is <math>\operatorname{false}\!</math> to the region where <math>q\!</math> is <math>\operatorname{true}.\!</math>

Figure&nbsp;1&prime; reprises the situation shown in Figure&nbsp;1, but adduces a new quality for the purpose of explaining what we know &mdash; now &mdash; we'll see in Figure&nbsp;2.

<center><pre>
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| X . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
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| . . . . . . o-------------o . o-------------o . . . . . . |
| . . h . . ./. . . . . . . .\./. . . . . . . .\. . . . . . |
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| . . . | . . . . . Q . . | . . . | . . dQ. . . . . | . . . |
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| . . . . . . o-------------o . o-------------o . . . . . . |
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o-----------------------------------------------------------o
</pre>
'''Figure 1&prime;.  Back, To The Future'''
</center>

This new quality, <math>\operatorname{d}q,\!</math> is an example of a ''differential quality'', since its absence or presence qualifies the absence or presence of change occurring in another quality.  As with any other quality, it is represented in the venn diagram by means of a "circle" that distinguishes two halves of the universe of discourse, in this case, outside and inside the region <math>\operatorname{d}Q.\!</math>