| Line 38: |
Line 38: |
| | Don't think about it — just compute: | | Don't think about it — just compute: |
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| − | {| align="center" cellpadding="6" width="90%" | + | {| align="center" cellpadding="10" |
| − | | align="center" |
| + | | [[Image:Cactus Graph (P,dP)(Q,dQ).jpg|500px]] |
| − | <pre>
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| − | o-------------------------------------------------o
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| − | | | | |
| − | | dp o o dq |
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| − | | / \ / \ |
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| − | | p o---@---o q |
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| − | | |
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| − | o-------------------------------------------------o
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| − | | (p, dp) (q, dq) |
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| − | o-------------------------------------------------o
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| − | </pre>
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| | |} | | |} |
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| − | To make future graphs easier to draw in ASCII, I will use devices like '''<code>@=@=@</code>''' and '''<code>o=o=o</code>''' to identify several nodes into one, as in this next redrawing:
| + | This expression follows because the expression <math>p + \operatorname{d}p,</math> where the plus sign indicates addition in <math>\mathbb{B},</math> that is, addition modulo 2, and thus corresponds to the exclusive disjunction operation in logic, parses to a graph of the following form: |
| − | | |
| − | {| align="center" cellpadding="6" width="90%"
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| − | | align="center" |
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| − | <pre>
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| − | o-------------------------------------------------o
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| − | | |
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| − | | p dp q dq |
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| − | | o---o o---o |
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| − | | \ | | / |
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| − | | \ | | / |
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| − | | \| |/ |
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| − | | @=@ |
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| − | | |
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| − | o-------------------------------------------------o
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| − | | (p, dp) (q, dq) |
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| − | o-------------------------------------------------o
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| − | </pre>
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| − | |}
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| − | | |
| − | However you draw it, these expressions follow because the expression <math>p + \operatorname{d}p,</math> where the plus sign indicates addition in <math>\mathbb{B},</math> that is, addition modulo 2, and thus corresponds to the exclusive disjunction operation in logic, parses to a graph of the following form:
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| | {| align="center" cellpadding="6" width="90%" | | {| align="center" cellpadding="6" width="90%" |