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| |+ style="height:30px" | <math>\text{Table 1.} ~~ \text{Syntax and Semantics of a Calculus for Propositional Logic}\!</math> | | |+ style="height:30px" | <math>\text{Table 1.} ~~ \text{Syntax and Semantics of a Calculus for Propositional Logic}\!</math> |
| |- style="height:40px; background:ghostwhite" | | |- style="height:40px; background:ghostwhite" |
| + | | <math>\text{Graph}\!</math> |
| | <math>\text{Expression}~\!</math> | | | <math>\text{Expression}~\!</math> |
| | <math>\text{Interpretation}\!</math> | | | <math>\text{Interpretation}\!</math> |
| | <math>\text{Other Notations}\!</math> | | | <math>\text{Other Notations}\!</math> |
| |- | | |- |
− | | | + | | height="100px" | [[Image:Cactus Node Big Fat.jpg|20px]] |
− | | <math>\text{True}\!</math> | + | | <math>~</math> |
| + | | <math>\operatorname{true}</math> |
| | <math>1\!</math> | | | <math>1\!</math> |
| |- | | |- |
− | | <math>\texttt{(~)}\!</math> | + | | height="100px" | [[Image:Cactus Spike Big Fat.jpg|20px]] |
− | | <math>\text{False}\!</math> | + | | <math>\texttt{(~)}</math> |
| + | | <math>\operatorname{false}</math> |
| | <math>0\!</math> | | | <math>0\!</math> |
| |- | | |- |
− | | <math>x\!</math> | + | | height="100px" | [[Image:Cactus A Big.jpg|20px]] |
− | | <math>x\!</math> | + | | <math>a\!</math> |
− | | <math>x\!</math> | + | | <math>a\!</math> |
| + | | <math>a\!</math> |
| |- | | |- |
− | | <math>\texttt{(} x \texttt{)}\!</math> | + | | height="120px" | [[Image:Cactus (A) Big.jpg|20px]] |
− | | <math>\text{Not}~ x\!</math> | + | | <math>\texttt{(} a \texttt{)}~</math> |
− | | | + | | <math>\operatorname{not}~ a</math> |
− | <math>\begin{matrix} | + | | <math>\lnot a \quad \bar{a} \quad \tilde{a} \quad a^\prime</math> |
− | x'
| |
− | \\
| |
− | \tilde{x} | |
− | \\ | |
− | \lnot x
| |
− | \end{matrix}\!</math>
| |
| |- | | |- |
− | | <math>x~y~z\!</math> | + | | height="100px" | [[Image:Cactus ABC Big.jpg|50px]] |
− | | <math>x ~\text{and}~ y ~\text{and}~ z\!</math> | + | | <math>a ~ b ~ c</math> |
− | | <math>x \land y \land z\!</math> | + | | <math>a ~\operatorname{and}~ b ~\operatorname{and}~ c</math> |
| + | | <math>a \land b \land c</math> |
| |- | | |- |
− | | <math>\texttt{((} x \texttt{)(} y \texttt{)(} z \texttt{))}\!</math> | + | | height="160px" | [[Image:Cactus ((A)(B)(C)) Big.jpg|65px]] |
− | | <math>x ~\text{or}~ y ~\text{or}~ z\!</math> | + | | <math>\texttt{((} a \texttt{)(} b \texttt{)(} c \texttt{))}</math> |
− | | <math>x \lor y \lor z\!</math> | + | | <math>a ~\operatorname{or}~ b ~\operatorname{or}~ c</math> |
| + | | <math>a \lor b \lor c</math> |
| |- | | |- |
− | | <math>\texttt{(} x ~ \texttt{(} y \texttt{))}\!</math> | + | | height="120px" | [[Image:Cactus (A(B)) Big.jpg|60px]] |
| + | | <math>\texttt{(} a \texttt{(} b \texttt{))}</math> |
| | | | | |
| <math>\begin{matrix} | | <math>\begin{matrix} |
− | x ~\text{implies}~ y
| + | a ~\operatorname{implies}~ b |
− | \\ | + | \\[6pt] |
− | \mathrm{If}~ x ~\text{then}~ y | + | \operatorname{if}~ a ~\operatorname{then}~ b |
| \end{matrix}</math> | | \end{matrix}</math> |
− | | <math>x \Rightarrow y\!</math> | + | | <math>a \Rightarrow b</math> |
| |- | | |- |
− | | <math>\texttt{(} x \texttt{,} y \texttt{)}\!</math> | + | | height="120px" | [[Image:Cactus (A,B) Big ISW.jpg|65px]] |
| + | | <math>\texttt{(} a \texttt{,} b \texttt{)}</math> |
| | | | | |
| <math>\begin{matrix} | | <math>\begin{matrix} |
− | x ~\text{not equal to}~ y
| + | a ~\operatorname{not~equal~to}~ b |
− | \\ | + | \\[6pt] |
− | x ~\text{exclusive or}~ y
| + | a ~\operatorname{exclusive~or}~ b |
| \end{matrix}</math> | | \end{matrix}</math> |
| | | | | |
| <math>\begin{matrix} | | <math>\begin{matrix} |
− | x \ne y
| + | a \neq b |
− | \\ | + | \\[6pt] |
− | x + y
| + | a + b |
| \end{matrix}</math> | | \end{matrix}</math> |
| |- | | |- |
− | | <math>\texttt{((} x \texttt{,} y \texttt{))}\!</math> | + | | height="160px" | [[Image:Cactus ((A,B)) Big.jpg|65px]] |
| + | | <math>\texttt{((} a \texttt{,} b \texttt{))}</math> |
| | | | | |
| <math>\begin{matrix} | | <math>\begin{matrix} |
− | x ~\text{is equal to}~ y
| + | a ~\operatorname{is~equal~to}~ b |
− | \\ | + | \\[6pt] |
− | x ~\text{if and only if}~ y
| + | a ~\operatorname{if~and~only~if}~ b |
| \end{matrix}</math> | | \end{matrix}</math> |
| | | | | |
| <math>\begin{matrix} | | <math>\begin{matrix} |
− | x = y
| + | a = b |
− | \\ | + | \\[6pt] |
− | x \Leftrightarrow y
| + | a \Leftrightarrow b |
| \end{matrix}</math> | | \end{matrix}</math> |
| |- | | |- |
− | | <math>\texttt{(} x \texttt{,} y \texttt{,} z \texttt{)}\!</math> | + | | height="120px" | [[Image:Cactus (A,B,C) Big.jpg|65px]] |
| + | | <math>\texttt{(} a \texttt{,} b \texttt{,} c \texttt{)}</math> |
| | | | | |
| <math>\begin{matrix} | | <math>\begin{matrix} |
− | \text{Just one of} | + | \operatorname{just~one~of} |
| \\ | | \\ |
− | x, y, z
| + | a, b, c |
| \\ | | \\ |
− | \text{is false}. | + | \operatorname{is~false}. |
| \end{matrix}</math> | | \end{matrix}</math> |
| | | | | |
| <math>\begin{matrix} | | <math>\begin{matrix} |
− | x'y~z~ & \lor
| + | & \bar{a} ~ b ~ c |
| \\ | | \\ |
− | x~y'z~ & \lor
| + | \lor & a ~ \bar{b} ~ c |
| \\ | | \\ |
− | x~y~z' &
| + | \lor & a ~ b ~ \bar{c} |
| \end{matrix}</math> | | \end{matrix}</math> |
| |- | | |- |
− | | <math>\texttt{((} x \texttt{),(} y \texttt{),(} z \texttt{))}\!</math> | + | | height="160px" | [[Image:Cactus ((A),(B),(C)) Big.jpg|65px]] |
| + | | <math>\texttt{((} a \texttt{),(} b \texttt{),(} c \texttt{))}</math> |
| | | | | |
| <math>\begin{matrix} | | <math>\begin{matrix} |
− | \text{Just one of} | + | \operatorname{just~one~of} |
− | \\
| |
− | x, y, z
| |
− | \\
| |
− | \text{is true}.
| |
| \\ | | \\ |
− | &
| + | a, b, c |
| \\ | | \\ |
− | \text{Partition all} | + | \operatorname{is~true}. |
| + | \\[6pt] |
| + | \operatorname{partition~all} |
| \\ | | \\ |
− | \text{into}~ x, y, z. | + | \operatorname{into}~ a, b, c. |
| \end{matrix}</math> | | \end{matrix}</math> |
| | | | | |
| <math>\begin{matrix} | | <math>\begin{matrix} |
− | x~y'z' & \lor
| + | & a ~ \bar{b} ~ \bar{c} |
| \\ | | \\ |
− | x'y~z' & \lor
| + | \lor & \bar{a} ~ b ~ \bar{c} |
| \\ | | \\ |
− | x'y'z~ &
| + | \lor & \bar{a} ~ \bar{b} ~ c |
| \end{matrix}</math> | | \end{matrix}</math> |
| |- | | |- |
| + | | height="160px" | [[Image:Cactus (A,(B,C)) Big.jpg|90px]] |
| + | | <math>\texttt{(} a \texttt{,(} b \texttt{,} c \texttt{))}</math> |
| | | | | |
| <math>\begin{matrix} | | <math>\begin{matrix} |
− | \texttt{((} x \texttt{,} y \texttt{),} z \texttt{)} | + | \operatorname{oddly~many~of} |
| \\ | | \\ |
− | &
| + | a, b, c |
| \\ | | \\ |
− | \texttt{(} x \texttt{,(} y \texttt{,} z \texttt{))} | + | \operatorname{are~true}. |
− | \end{matrix}\!</math>
| + | \end{matrix}</math> |
− | |
| |
− | <math>\begin{matrix}
| |
− | \text{Oddly many of}
| |
− | \\
| |
− | x, y, z
| |
− | \\
| |
− | \text{are true}.
| |
− | \end{matrix}\!</math> | |
| | | | | |
− | <p><math>x + y + z\!</math></p> | + | <p><math>a + b + c\!</math></p> |
| <br> | | <br> |
| <p><math>\begin{matrix} | | <p><math>\begin{matrix} |
− | x~y~z~ & \lor
| + | & a ~ b ~ c |
| \\ | | \\ |
− | x~y'z' & \lor
| + | \lor & a ~ \bar{b} ~ \bar{c} |
| \\ | | \\ |
− | x'y~z' & \lor
| + | \lor & \bar{a} ~ b ~ \bar{c} |
| \\ | | \\ |
− | x'y'z~ &
| + | \lor & \bar{a} ~ \bar{b} ~ c |
− | \end{matrix}\!</math></p> | + | \end{matrix}</math></p> |
| |- | | |- |
− | | <math>\texttt{(} w \texttt{,(} x \texttt{),(} y \texttt{),(} z \texttt{))}\!</math> | + | | height="160px" | [[Image:Cactus (X,(A),(B),(C)) Big.jpg|90px]] |
| + | | <math>\texttt{(} x \texttt{,(} a \texttt{),(} b \texttt{),(} c \texttt{))}</math> |
| | | | | |
| <math>\begin{matrix} | | <math>\begin{matrix} |
− | \text{Partition}~ w | + | \operatorname{partition}~ x |
| \\ | | \\ |
− | \text{into}~ x, y, z. | + | \operatorname{into}~ a, b, c. |
| + | \\[6pt] |
| + | \operatorname{genus}~ x ~\operatorname{comprises} |
| \\ | | \\ |
− | &
| + | \operatorname{species}~ a, b, c. |
− | \\ | |
− | \text{Genus}~ w ~\text{comprises}
| |
− | \\
| |
− | \text{species}~ x, y, z.
| |
| \end{matrix}</math> | | \end{matrix}</math> |
| | | | | |
| <math>\begin{matrix} | | <math>\begin{matrix} |
− | w'x'y'z' & \lor
| + | & \bar{x} ~ \bar{a} ~ \bar{b} ~ \bar{c} |
| \\ | | \\ |
− | w~x~y'z' & \lor
| + | \lor & x ~ a ~ \bar{b} ~ \bar{c} |
| \\ | | \\ |
− | w~x'y~z' & \lor
| + | \lor & x ~ \bar{a} ~ b ~ \bar{c} |
| \\ | | \\ |
− | w~x'y'z~ &
| + | \lor & x ~ \bar{a} ~ \bar{b} ~ c |
| \end{matrix}</math> | | \end{matrix}</math> |
| |} | | |} |
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| A sketch of this work is presented in the following series of Figures, where each logical proposition is expanded over the basic cells <math>uv, u \texttt{(} v \texttt{)}, \texttt{(} u \texttt{)} v, \texttt{(} u \texttt{)(} v \texttt{)}\!</math> of the 2-dimensional universe of discourse <math>U^\bullet = [u, v].\!</math> | | A sketch of this work is presented in the following series of Figures, where each logical proposition is expanded over the basic cells <math>uv, u \texttt{(} v \texttt{)}, \texttt{(} u \texttt{)} v, \texttt{(} u \texttt{)(} v \texttt{)}\!</math> of the 2-dimensional universe of discourse <math>U^\bullet = [u, v].\!</math> |
| | | |
− | ===Computation Summary : <math>f(u, v) = \texttt{((u)(v))}</math>=== | + | ===Computation Summary for Logical Disjunction=== |
| | | |
− | The venn diagram in Figure 1.1 shows how the proposition <math>f = \texttt{((u)(v))}</math> can be expanded over the universe of discourse <math>[u, v]\!</math> to produce a logically equivalent exclusive disjunction, namely, <math>\texttt{uv~+~u(v)~+~(u)v}.</math> | + | The venn diagram in Figure 1.1 shows how the proposition <math>f = \texttt{((} u \texttt{)(} v \texttt{))}\!</math> can be expanded over the universe of discourse <math>[u, v]\!</math> to produce a logically equivalent exclusive disjunction, namely, <math>uv + u \texttt{(} v \texttt{)} + \texttt{(} u \texttt{)} v.\!</math> |
| | | |
| {| align="center" border="0" cellpadding="10" | | {| align="center" border="0" cellpadding="10" |
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| |} | | |} |
| | | |
− | Figure 1.2 expands <math>\mathrm{E}f = \texttt{((u + du)(v + dv))}</math> over <math>[u, v]\!</math> to give: | + | Figure 1.2 expands <math>\mathrm{E}f = \texttt{((} u + \mathrm{d}u \texttt{)(} v + \mathrm{d}v \texttt{))}\!</math> over <math>[u, v]\!</math> to give: |
| | | |
− | {| align="center" cellpadding="8" width="90%" | + | {| align="center" cellpadding="8" |
− | | <math>\texttt{uv~(du~dv) ~+~ u(v)~(du (dv)) ~+~ (u)v~((du) dv) ~+~ (u)(v)~((du)(dv))}</math> | + | | |
| + | <math>\begin{matrix} |
| + | \mathrm{E}\texttt{((} u \texttt{)(} v \texttt{))} |
| + | & = & uv \cdot \texttt{(} \mathrm{d}u ~ \mathrm{d}v \texttt{)} |
| + | & + & u \texttt{(} v \texttt{)} \cdot \texttt{(} \mathrm{d}u \texttt{(} \mathrm{d}v \texttt{))} |
| + | & + & \texttt{(} u \texttt{)} v \cdot \texttt{((} \mathrm{d}u \texttt{)} \mathrm{d}v \texttt{)} |
| + | & + & \texttt{(} u \texttt{)(} v \texttt{)} \cdot \texttt{((} \mathrm{d}u \texttt{)(} \mathrm{d}v \texttt{))} |
| + | \end{matrix}</math> |
| |} | | |} |
| | | |
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| |} | | |} |
| | | |
− | Figure 1.3 expands <math>\mathrm{D}f = f + \mathrm{E}f</math> over <math>[u, v]\!</math> to produce: | + | Figure 1.3 expands <math>\mathrm{D}f = f + \mathrm{E}f\!</math> over <math>[u, v]\!</math> to produce: |
| | | |
− | {| align="center" cellpadding="8" width="90%" | + | {| align="center" cellpadding="8" |
− | | <math>\texttt{uv~du~dv ~+~ u(v)~du(dv) ~+~ (u)v~(du)dv ~+~ (u)(v)~((du)(dv))}</math> | + | | |
| + | <math>\begin{matrix} |
| + | \mathrm{D}\texttt{((} u \texttt{)(} v \texttt{))} |
| + | & = & uv \cdot \mathrm{d}u ~ \mathrm{d}v |
| + | & + & u \texttt{(} v \texttt{)} \cdot \mathrm{d}u \texttt{(} \mathrm{d}v \texttt{)} |
| + | & + & \texttt{(} u \texttt{)} v \cdot \texttt{(} \mathrm{d}u \texttt{)} \mathrm{d}v |
| + | & + & \texttt{(} u \texttt{)(} v \texttt{)} \cdot \texttt{((} \mathrm{d}u \texttt{)(} \mathrm{d}v \texttt{))} |
| + | \end{matrix}</math> |
| |} | | |} |
| | | |
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| I'll break this here in case anyone wants to try and do the work for <math>g\!</math> on their own. | | I'll break this here in case anyone wants to try and do the work for <math>g\!</math> on their own. |
| | | |
− | ===Computation Summary : <math>g(u, v) = \texttt{((u,~v))}</math>=== | + | ===Computation Summary for Logical Equality=== |
| | | |
− | The venn diagram in Figure 2.1 shows how the proposition <math>g = \texttt{((u,~v))}</math> can be expanded over the universe of discourse <math>[u, v]\!</math> to produce a logically equivalent exclusive disjunction, namely, <math>\texttt{uv ~+~ (u)(v)}.</math> | + | The venn diagram in Figure 2.1 shows how the proposition <math>g = \texttt{((} u \texttt{,~} v \texttt{))}\!</math> can be expanded over the universe of discourse <math>[u, v]\!</math> to produce a logically equivalent exclusive disjunction, namely, <math>uv + \texttt{(} u \texttt{)(} v \texttt{)}.\!</math> |
| | | |
| {| align="center" border="0" cellpadding="10" | | {| align="center" border="0" cellpadding="10" |
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| |} | | |} |
| | | |
− | Figure 2.2 expands <math>\mathrm{E}g = \texttt{((u + du,~v + dv))}</math> over <math>[u, v]\!</math> to give: | + | Figure 2.2 expands <math>\mathrm{E}g = \texttt{((} u + \mathrm{d}u \texttt{,~} v + \mathrm{d}v \texttt{))}\!</math> over <math>[u, v]\!</math> to give: |
| | | |
− | {| align="center" cellpadding="8" width="90%" | + | {| align="center" cellpadding="8" |
− | | <math>\texttt{uv~((du,~dv)) ~+~ u(v)~(du,~dv) ~+~ (u)v~(du,~dv) ~+~ (u)(v)~((du,~dv))}</math> | + | | |
| + | <math>\begin{matrix} |
| + | \mathrm{E}\texttt{((} u \texttt{,~} v \texttt{))} |
| + | & = & uv \cdot \texttt{((} \mathrm{d}u \texttt{,~} \mathrm{d}v \texttt{))} |
| + | & + & u \texttt{(} v \texttt{)} \cdot \texttt{(} \mathrm{d}u \texttt{,~} \mathrm{d}v \texttt{)} |
| + | & + & \texttt{(} u \texttt{)} v \cdot \texttt{(} \mathrm{d}u \texttt{,~} \mathrm{d}v \texttt{)} |
| + | & + & \texttt{(} u \texttt{)(} v \texttt{)} \cdot \texttt{((} \mathrm{d}u \texttt{,~} \mathrm{d}v \texttt{))} |
| + | \end{matrix}</math> |
| |} | | |} |
| | | |
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| |} | | |} |
| | | |
− | Figure 2.3 expands <math>\mathrm{D}g = g + \mathrm{E}g</math> over <math>[u, v]\!</math> to yield the form: | + | Figure 2.3 expands <math>\mathrm{D}g = g + \mathrm{E}g\!</math> over <math>[u, v]\!</math> to yield the form: |
| | | |
− | {| align="center" cellpadding="8" width="90%" | + | {| align="center" cellpadding="8" |
− | | <math>\texttt{uv~(du,~dv) ~+~ u(v)~(du,~dv) ~+~ (u)v~(du,~dv) ~+~ (u)(v)~(du,~dv)}\!</math> | + | | |
| + | <math>\begin{matrix} |
| + | \mathrm{D}\texttt{((} u \texttt{,~} v \texttt{))} |
| + | & = & uv \cdot \texttt{(} \mathrm{d}u \texttt{,~} \mathrm{d}v \texttt{)} |
| + | & + & u \texttt{(} v \texttt{)} \cdot \texttt{(} \mathrm{d}u \texttt{,~} \mathrm{d}v \texttt{)} |
| + | & + & \texttt{(} u \texttt{)} v \cdot \texttt{(} \mathrm{d}u \texttt{,~} \mathrm{d}v \texttt{)} |
| + | & + & \texttt{(} u \texttt{)(} v \texttt{)} \cdot \texttt{(} \mathrm{d}u \texttt{,~} \mathrm{d}v \texttt{)} |
| + | \end{matrix}</math> |
| |} | | |} |
| | | |
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| | | | | |
| <math>\begin{array}{lllll} | | <math>\begin{array}{lllll} |
− | F & = & (f, g) & = & ( ~\texttt{((u)(v))}~ , ~\texttt{((u,~v))}~ ). | + | F |
| + | & = & (f, g) |
| + | & = & ( ~ \texttt{((} u \texttt{)(} v \texttt{))} ~,~ \texttt{((} u \texttt{,~} v \texttt{))} ~ ) |
| \end{array}</math> | | \end{array}</math> |
| |} | | |} |
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| To speed things along, I will skip a mass of motivating discussion and just exhibit the simplest form of a differential <math>\mathrm{d}F\!</math> for the current example of a logical transformation <math>F,\!</math> after which the majority of the easiest questions will have been answered in visually intuitive terms. | | To speed things along, I will skip a mass of motivating discussion and just exhibit the simplest form of a differential <math>\mathrm{d}F\!</math> for the current example of a logical transformation <math>F,\!</math> after which the majority of the easiest questions will have been answered in visually intuitive terms. |
| | | |
− | For <math>F = (f, g)\!</math> we have <math>\mathrm{d}F = (\mathrm{d}f, \mathrm{d}g),</math> and so we can proceed componentwise, patching the pieces back together at the end. | + | For <math>F = (f, g)\!</math> we have <math>\mathrm{d}F = (\mathrm{d}f, \mathrm{d}g),\!</math> and so we can proceed componentwise, patching the pieces back together at the end. |
| | | |
| We have prepared the ground already by computing these terms: | | We have prepared the ground already by computing these terms: |
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| | | | | |
| <math>\begin{array}{lll} | | <math>\begin{array}{lll} |
− | \mathrm{E}f & = & \texttt{(( u + du )( v + dv ))} | + | \mathrm{E}f & = & \texttt{((} u + \mathrm{d}u \texttt{)(} v + \mathrm{d}v \texttt{))} |
− | \\ \\ | + | \\[8pt] |
− | \mathrm{E}g & = & \texttt{(( u + du ,~ v + dv ))} | + | \mathrm{E}g & = & \texttt{((} u + \mathrm{d}u \texttt{,~} v + \mathrm{d}v \texttt{))} |
− | \\ \\ | + | \\[8pt] |
− | \mathrm{D}f & = & \texttt{((u)(v)) ~+~ (( u + du )( v + dv ))} | + | \mathrm{D}f & = & \texttt{((} u \texttt{)(} v \texttt{))} ~+~ \texttt{((} u + \mathrm{d}u \texttt{)(} v + \mathrm{d}v \texttt{))} |
− | \\ \\ | + | \\[8pt] |
− | \mathrm{D}g & = & \texttt{((u,~v)) ~+~ (( u + du ,~ v + dv ))} | + | \mathrm{D}g & = & \texttt{((} u \texttt{,~} v \texttt{))} ~+~ \texttt{((} u + \mathrm{d}u \texttt{,~} v + \mathrm{d}v \texttt{))} |
− | \end{array}\!</math> | + | \end{array}</math> |
| |} | | |} |
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− | As a matter of fact, computing the symmetric differences <math>\mathrm{D}f = f + \mathrm{E}f</math> and <math>\mathrm{D}g = g + \mathrm{E}g</math> has already taken care of the ''localizing'' part of the task by subtracting out the forms of <math>f\!</math> and <math>g\!</math> from the forms of <math>\mathrm{E}f</math> and <math>\mathrm{E}g,</math> respectively. Thus all we have left to do is to decide what linear propositions best approximate the difference maps <math>\mathrm{D}f</math> and <math>\mathrm{D}g,</math> respectively. | + | As a matter of fact, computing the symmetric differences <math>\mathrm{D}f = f + \mathrm{E}f\!</math> and <math>\mathrm{D}g = g + \mathrm{E}g\!</math> has already taken care of the ''localizing'' part of the task by subtracting out the forms of <math>f\!</math> and <math>g\!</math> from the forms of <math>\mathrm{E}f\!</math> and <math>\mathrm{E}g,\!</math> respectively. Thus all we have left to do is to decide what linear propositions best approximate the difference maps <math>{\mathrm{D}f}\!</math> and <math>{\mathrm{D}g},\!</math> respectively. |
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| This raises the question: What is a linear proposition? | | This raises the question: What is a linear proposition? |
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− | The answer that makes the most sense in this context is this: A proposition is just a boolean-valued function, so a linear proposition is a linear function into the boolean space <math>\mathbb{B}.</math> | + | The answer that makes the most sense in this context is this: A proposition is just a boolean-valued function, so a linear proposition is a linear function into the boolean space <math>\mathbb{B}.\!</math> |
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− | In particular, the linear functions that we want will be linear functions in the differential variables <math>du\!</math> and <math>dv.\!</math> | + | In particular, the linear functions that we want will be linear functions in the differential variables <math>\mathrm{d}u\!</math> and <math>\mathrm{d}v.\!</math> |
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− | As it turns out, there are just four linear propositions in the associated ''differential universe'' <math>\mathrm{d}U^\bullet = [du, dv],</math> and these are the propositions that are commonly denoted: <math>\texttt{0}, \texttt{du}, \texttt{dv}, \texttt{du + dv},</math> in other words, <math>\texttt{()}, \texttt{du}, \texttt{dv}, \texttt{(du, dv)}.</math> | + | As it turns out, there are just four linear propositions in the associated ''differential universe'' <math>\mathrm{d}U^\bullet = [\mathrm{d}u, \mathrm{d}v].\!</math> These are the propositions that are commonly denoted: <math>{0, ~\mathrm{d}u, ~\mathrm{d}v, ~\mathrm{d}u + \mathrm{d}v},\!</math> in other words: <math>\texttt{(~)}, ~\mathrm{d}u, ~\mathrm{d}v, ~\texttt{(} \mathrm{d}u \texttt{,~} \mathrm{d}v \texttt{)}.\!</math> |
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| ==Notions of Approximation== | | ==Notions of Approximation== |