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| ====Peirce's law==== | | ====Peirce's law==== |
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− | : ''Main article : [[Peirce's law]] | + | : ''Main article'' : [[Peirce's law]] |
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| Peirce's law is commonly written in the following form: | | Peirce's law is commonly written in the following form: |
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− | <center>
| + | {| align="center" cellpadding="10" |
− | <p><math>((p \Rightarrow q) \Rightarrow p) \Rightarrow p</math></p>
| + | | <math>((p \Rightarrow q) \Rightarrow p) \Rightarrow p</math> |
− | </center>
| + | |} |
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| The existential graph representation of Peirce's law is shown in Figure 12. | | The existential graph representation of Peirce's law is shown in Figure 12. |
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− | {| align="center" border="0" cellpadding="10" cellspacing="0" | + | {| align="center" cellpadding="10" |
| | [[Image:PERS_Figure_12.jpg|500px]] || (12) | | | [[Image:PERS_Figure_12.jpg|500px]] || (12) |
| |} | | |} |
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| A graphical proof of Peirce's law is shown in Figure 13. | | A graphical proof of Peirce's law is shown in Figure 13. |
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− | {| align="center" border="0" cellpadding="10" cellspacing="0" | + | {| align="center" cellpadding="10" |
| | [[Image:PERS_Figure_13.jpg|500px]] || (13) | | | [[Image:PERS_Figure_13.jpg|500px]] || (13) |
| |} | | |} |
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| An illustrious example of a propositional theorem is the ''praeclarum theorema'', the ''admirable'', ''shining'', or ''splendid'' theorem of Leibniz. | | An illustrious example of a propositional theorem is the ''praeclarum theorema'', the ''admirable'', ''shining'', or ''splendid'' theorem of Leibniz. |
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− | {| align="center" cellpadding="8" width="90%" | + | {| align="center" cellpadding="10" width="90%" |
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| <p>If ''a'' is ''b'' and ''d'' is ''c'', then ''ad'' will be ''bc''.</p> | | <p>If ''a'' is ''b'' and ''d'' is ''c'', then ''ad'' will be ''bc''.</p> |