[FOM] Re: branching quantifiers
Thomas Forster
T.Forster at dpmms.cam.ac.uk
Sun Apr 11 13:25:19 EDT 2004
Thank you very much for this. I know about Blass-Gurevich and the
NP-completeness. And Fagin and Walkoe... But - i repeat - what about
*width* of quantifier prefixes? I think i have proved that every
$\forall_{2n}$ formula ($2n$ alternations of quantifiers with the first
block universal) is equivalent to a branching-quantifier formula whose
prefix is of width $n$ and where every row is \forall^* \exists^*. Is
this known?
I didn't know about decidablity of the monadic fragment, tho' it doesn't
surprise me. But what is the strength of the *polyadic* fragment
without
equality?
Thomas Forster
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