Changes

Since the expression <math>\texttt{(} p \texttt{(} q \texttt{))(} p \texttt{(} r \texttt{))}</math> involves just three variables, it may be worth the trouble to draw a venn diagram of the situation.  There are in fact two different ways to execute the picture.

Since the expression <math>\texttt{(} p \texttt{(} q \texttt{))(} p \texttt{(} r \texttt{))}</math> involves just three variables, it may be worth the trouble to draw a venn diagram of the situation.  There are in fact two different ways to execute the picture.

Figure&nbsp;1 indicates the points of the universe of discourse <math>X\!</math> for which the proposition <math>f : X \to \mathbb{B}</math> has the value 1, here interpreted as the logical value <math>\operatorname{true}.</math>  In this ''paint by numbers'' style of picture, one simply paints over the cells of a generic template for the universe <math>X,\!</math> going according to some previously adopted convention, for instance:  Let the cells that get the value 0 under <math>f\!</math> remain untinted and let the cells that get the value 1 under <math>f\!</math> be painted or shaded.  In doing this, it may be good to remind ourselves that the value of the picture as a whole is not in the ''paints'', in other words, the <math>0, 1\!</math> in <math>\mathbb{B},</math> but in the pattern of regions that they indicate. (Note.  In this Ascii version, I use [&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;] for 0 and [&nbsp;`&nbsp;`&nbsp;`&nbsp;] for 1.)

Figure&nbsp;1 indicates the points of the universe of discourse <math>X\!</math> for which the proposition <math>f : X \to \mathbb{B}</math> has the value 1, here interpreted as the logical value <math>\operatorname{true}.</math>  In this ''paint by numbers'' style of picture, one simply paints over the cells of a generic template for the universe <math>X,\!</math> going according to some previously adopted convention, for instance:  Let the cells that get the value 0 under <math>f\!</math> remain untinted and let the cells that get the value 1 under <math>f\!</math> be painted or shaded.  In doing this, it may be good to remind ourselves that the value of the picture as a whole is not in the ''paints'', in other words, the <math>0, 1\!</math> in <math>\mathbb{B},</math> but in the pattern of regions that they indicate.

{| align="center" cellpadding="10" style="text-align:center; width:90%"

{| align="center" cellpadding="8" style="text-align:center"

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| [[Image:Venn Diagram (P (Q)) (P (R)).jpg|500px]] || (27)

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| <math>\text{Venn Diagram for}~ \texttt{(} p \texttt{~(} q \texttt{))~(} p \texttt{~(} r \texttt{))}</math>

| ` ` ` ` ` ` ` `|            P           |` ` ` ` ` ` ` ` |

| ` ` ` | ` ` ` Q ` ` ` ` | ` ` ` | ` ` ` ` R ` ` ` | ` ` ` |

| ` ` ` | ` ` ` ` ` ` ` ` | ` ` ` | ` ` ` ` ` ` ` ` | ` ` ` |

| ` ` ` o ` ` ` ` ` ` ` ` o ` ` ` o ` ` ` ` ` ` ` ` o ` ` ` |

| ` ` ` `\` ` ` ` ` ` ` ` `\` ` `/` ` ` ` ` ` ` ` `/` ` ` ` |

Figure 27.  Venn Diagram for (p (q))(p (r))

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o-----------------------------------------------------------o

o-----------------------------------------------------------o

Figure 28.  Venn Diagram for (p (q r))

Venn Diagram for (p (q r))

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