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The phases of an eight-phase dual-ring intersection provide an interesting example of a non-transitive relation.
Let !!a!! and !!b!! be phases, and write !!a\sim b!! when the phases are compatible, which means that traffic making those movements will not collide. This relation is reflexive and symmetric, but not transitive, because for example we have !!\Phi6\sim \Phi1!! and !!\Phi1\sim \Phi5!! but not !!\Phi6\sim\Phi 5!!. A mathematician would have numbered the phases differently, but even with the standard numbering the rule is not too complicated: $$ a\sim b \text{ when any of these holds:} \begin{cases} a\in\{\Phi1, \Phi 2\}\text{ and }b\in\{\Phi5, \Phi6\},\text{ or} \\ a\in\{\Phi3, \Phi 4\}\text{ and }b\in\{\Phi7, \Phi8\},\text{ or} \\ a = b \end{cases} $$
Soon, perhaps tomorrow, I will post about lipograms again, and this is my pre-commitment that I will not try to turn the post into a lipogram. Also I will not try to go the other direction and write it to omit all the other vowels. I was tempted to end this note with “Yow! Am I having fun?” but I am not going to do it. That last phrase was e-less but it was by accident. But now I want to go back and fix — arrgh I am doing it again! —ARRGH — thE rEst of thE SENTENCE. HA, THERE. I WILL RESIST. EEEEEEEEEEEEEEEEEEEEEEEeeeeeeeeeeeeeeeeee e e e
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