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TeX doesn't appear to be able to overlay symbols, or at least it isn't covered in the documentation. The causal modal operators should be a "c" inside a square and diamond. CyborgTosser ( Only half the battle) 07:30, 10 January 2007 (UTC) reply

With the possible exception of P, all of the axioms are controversial. At least, they are so absent some more detailed description of a more constrained meaning. —Preceding unsigned comment added by 82.6.117.146 ( talk) 00:00, 1 September 2010 (UTC) reply