Michael Beeson's Research

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The posted input files are now all mechanically generated from a master list of theorems.

The times shown in the following table are not the times required to find the proof, but rather the maximum time allocated to Otter to find the proof. The time is shown only when it had to be longer than the default, which was often 20 seconds when hints were used and 120 seconds when hints were not used.

For more information about our methodology see the top page of this project.

Input File Proof Length Strategy Seconds Commentary
Satz5.1 Satz5.1.prf 127 hints Connectivity of betweenness
(Gupta 1965, one of Quaife's challenge problems)
$a \neq b \land T(a,b,c) \land T(a,b,d) \rightarrow T(a,c,d) \lor T(a,d,c)$
Wos has subsequently found a 96-step proof.
Satz5.2 Satz5.2.prf 3 $a \neq b \land T(a,b,c) \land T(a,b,d) \rightarrow T(b,c,d) \lor T(b,d,c) $
Satz5.3 Satz5.3.prf 15 $ T(a,b,d) \land T(a,c,d) \rightarrow T(a,b,c) \lor T(a,c,b) $
Satz5.5a Satz5.5a.prf 17 left to right of Satz 5.5
Satz5.5b Satz5.5b.prf 8 right to left of Satz 5.5
Satz5.6 Satz5.6.prf 7 $\le$ respects congruence
Satz5.7 Satz5.7.prf 1 reflexivity of $ \le $
Satz5.8 Satz5.8.prf 8 transitivity of $ \le $
Satz5.9 Satz5.9.prf 20 diagram $ ab \le cd \land cd \le ef \rightarrow ab \le cd $
Satz5.10 Satz5.10.prf 5 $ ab \le cd \lor cd \le ab $
Satz5.11 Satz5.11.prf 1 $ aa \le cd $
Satz5.12a1 Satz5.12a1.prf 1 $Col(a,b,c) \land T(a,b,c) \rightarrow ab \le ac \land bc \le ac $
Satz5.12a2 Satz5.12a2.prf 2 $ Col(a,b,c) \land T(a,b,c)\rightarrow bc \le ac $
NarbouxLemma1 NarbouxLemma1.prf 4 $ T(a,b,c) \land E(a,c,a,b)\rightarrow c=b $
We used this to prove 5.12b (and almost certainly nowhere else). Narboux needed this in his formalization too.
Satz5.12b Satz5.12b.prf 20 subformula 227 $ Col(a,b,c) \land ab \le ac \land bc \le ac \rightarrow T(a,b,c) $

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