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Nate Hayes wrote:
Arnold Neumaier wrote:3. Concerning the values of the other decoration trits, I think that this is part of a general observation that not all combinations of trit values make sense. Indeed, assuming the four trits v=valid, d=-defined, c=continuous, b=bounded (which are the indispensible ones) and the possible values + (True), - (False), and 0 (no claim), only 10 combinations of trits are computationally relevant and should be allowed: v d c b | #cases - 0 0 0 | 1 + - 0 0 | 1 + 0 0 0- | 2 + + +0 +0- | 6 (In particular, v is never 0 and c is never -.)
A further observation is that "v" is never + when all other decorations are 0, hence "v" (what I believe John is referring to as the "illform" bit) is completely unnecesary.
This is not correct. +000 can arise: x = sign([-1,1]) is ([-1,1],++0+) y = sqrt(x) is ([0,1],+000) Thus v is needed.
I'm fairly certain the only decorations IEEE 1788 needs are "defined", "continuous", and "bounded".
We need all four. But we can dispense with the ohers.