On Tue, Mar 10, 2009 at 07:16:50AM -0400, Christopher Hickman wrote: >> more pyramids. The null koan is an obvious variant that lots of >> people allow, but I prefer to disallow it because of the ambiguity of >> rules like "contains only grounded pyramids". > > Could somebody explain the ambiguity of this rule in relation to the null > koan? Clearly the null koan doesn't contain any pyramids, let alone only > grounded ones. How could anyone think this could be marked anything but > no? Most people I know with a background in mathematics/symbolic logic would mark the null koan white for this rule, as it is "vacuously true". Generally, propositions about sets which require something to be true for all elements of the set are true for the empty set. Here, it is the case that *every* pyramid in the null koan is grounded; if it were false, there would have to be a pyramid which is ungrounded. If you play with the null koan in a mixed group, some people will consider rules to require a special exception for the null koan, which, like people disagreeing about the definition of primes, doesn't invalidate the rule, but probably makes the rule harder to guess for the players who define things differently than the Master.
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