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| visits | member for | 2 years, 5 months |
| seen | May 10 at 6:08 | |
| stats | profile views | 317 |
Dear All,
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Have Fun
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Apr 26 |
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Less absorption in Minimal Logic? Yes, sounds good! |
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Apr 26 |
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Less absorption in Minimal Logic? So you assume inversion for conjunction, i.e. if A |- B /\ C, then A |- B and A |- C? To make the argument go through? |
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Apr 26 |
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Less absorption in Minimal Logic? This is a kind of a tex challenge for me. |
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Apr 26 |
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Less absorption in Minimal Logic? Now the comment /* not derivable */ is gone, and it looks as I state something true. Can this comment be restored in math? |
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Jan 11 |
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Antique handling of consequentia mirabilis? @PeterSmith sorry, my fault. Was thinking in terms of minimal logic where one additionally assumes /A = A -> f. |
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Jan 11 |
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Antique handling of consequentia mirabilis? Yes, the natural deduction formulation does the same. Any particular reason to use /A instead of ~A? Is this historical more adequate? |
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Dec 13 |
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How to deduce that something does not follow? Very nice derivation, thanks. When H is consistent then we cannot have H |- Q and H |- ~Q, therefore also not P |- Q. |
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Oct 12 |
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Natural order of rational trees? Is it decidable for rational trees? |
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Oct 10 |
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Natural order of rational trees? Yes, roots are important. T = s(s(T,1),0) is not the same as S = s(s(S,0),1). |
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Jul 8 |
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Sum set fixpoint, how many iterations? Remark for the interested reader, if the lemma holds for sets S_i, it would also hold for integer intervals I_i, since an interval is only a special case of a set. |
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Jul 8 |
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Sum set fixpoint, how many iterations? Maybe an alternate proof could use monotonicity of Minkowsky sum, i.e. A subset B implies A + C subset B + C. Not sure. But I am already happy to see the question settled. |
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Jul 8 |
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Sum set fixpoint, how many iterations? Ok I guess the argument runs along the following for a x_i in S^0_i \ S^1_i there was anyway no (x_j)_j<>i, so when "deleting" x_i from S^0_i it will not reduce any of the S^0_j for j<>i. |
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Jul 8 |
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Sum set fixpoint, how many iterations? Was also hypothesizing once that the fixpoint is reached after maximal 1 iteration. Did not yet have time to produce a counter example. What is exactly the argument behind S^2_i = S^1_i in the general case? |
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Jul 6 |
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Sum set fixpoint, how many iterations? It looks the problem can be reduced to y_1 + .. + y_n + b = 0, by using y_i = a_i * x_i. We can also find sets T_i with y_i in T_i, by T_i = a_i * S_i. And then ask for fixpoint of (T_1,..,T_n). |
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Jul 4 |
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Sum set fixpoint, how many iterations? In the case of n=2 a simple geometric argument shows that l=<1 is sufficient. Right? But for n>2, is there also a fixed bound? |
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Jul 4 |
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Sum set fixpoint, how many iterations? I thought it is the other way around by construction of the mapping, i.e. S_i^k+1 subset S_i^k. But otherwise I agree, this is the worst case. But is it possible that it happens? |
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Mar 18 |
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Contradiction Theorem Mind you, it should read the step from ~~A to A. And my reference is wrong. |
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Mar 18 |
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Contradiction Theorem You're welcome. (Means: I would be pleased, english for "Bitteschön - Dank erwidernd"). |
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Mar 18 |
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Contradiction Theorem I know, but I ALWAYS use ASCII art. And damned, this stack exchange is too stupid to change it automatically into what they prefer. |
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Mar 15 |
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Disjunction in Intuitionistic Logic, what about $((P \to U \lor V) \to Z)$ Just fixed U=1. |
