482 research outputs found
On generalized Frame-Stewart numbers
For the multi-peg Tower of Hanoi problem with pegs, so far
the best solution is obtained by the Stewart's algorithm based on the the
following recurrence relation: ,
. In this paper, we generalize this recurrence
relation to ,
, for two sequences of
arbitrary positive integers and
and we show that the sequence of
differences consists of numbers of the form , with
for all , arranged in nondecreasing order. We also apply this result to
analyze recurrence relations for the Tower of Hanoi problems on several graphs.Comment: 13 pages ; 3 figure
A proof of P!=NP
We show that it is provable in PA that there is an arithmetically definable
sequence of -sentences, such that
- PRA+ is -sound and
-complete
- the length of is bounded above by a polynomial function of
with positive leading coefficient
- PRA+ always proves 1-consistency of PRA+.
One has that the growth in logical strength is in some sense "as fast as
possible", manifested in the fact that the total general recursive functions
whose totality is asserted by the true -sentences in the sequence
are cofinal growth-rate-wise in the set of all total general recursive
functions. We then develop an argument which makes use of a sequence of
sentences constructed by an application of the diagonal lemma, which are
generalisations in a broad sense of Hugh Woodin's "Tower of Hanoi" construction
as outlined in his essay "Tower of Hanoi" in Chapter 18 of the anthology "Truth
in Mathematics". The argument establishes the result that it is provable in PA
that . We indicate how to pull the argument all the way down into
EFA
Diameters, distortion and eigenvalues
We study the relation between the diameter, the first positive eigenvalue of
the discrete -Laplacian and the -distortion of a finite graph. We
prove an inequality relating these three quantities and apply it to families of
Cayley and Schreier graphs. We also show that the -distortion of Pascal
graphs, approximating the Sierpinski gasket, is bounded, which allows to obtain
estimates for the convergence to zero of the spectral gap as an application of
the main result.Comment: Final version, to appear in the European Journal of Combinatoric
Fatal Attractors in Parity Games: Building Blocks for Partial Solvers
Attractors in parity games are a technical device for solving "alternating"
reachability of given node sets. A well known solver of parity games -
Zielonka's algorithm - uses such attractor computations recursively. We here
propose new forms of attractors that are monotone in that they are aware of
specific static patterns of colors encountered in reaching a given node set in
alternating fashion. Then we demonstrate how these new forms of attractors can
be embedded within greatest fixed-point computations to design solvers of
parity games that run in polynomial time but are partial in that they may not
decide the winning status of all nodes in the input game.
Experimental results show that our partial solvers completely solve
benchmarks that were constructed to challenge existing full solvers. Our
partial solvers also have encouraging run times in practice. For one partial
solver we prove that its run-time is at most cubic in the number of nodes in
the parity game, that its output game is independent of the order in which
monotone attractors are computed, and that it solves all Buechi games and weak
games.
We then define and study a transformation that converts partial solvers into
more precise partial solvers, and we prove that this transformation is sound
under very reasonable conditions on the input partial solvers. Noting that one
of our partial solvers meets these conditions, we apply its transformation on
1.6 million randomly generated games and so experimentally validate that the
transformation can be very effective in increasing the precision of partial
solvers
Loopless Gray Code Enumeration and the Tower of Bucharest
We give new algorithms for generating all n-tuples over an alphabet of m letters, changing only one letter at a time (Gray codes). These algorithms are based on the connection with variations of the Towers of Hanoi game. Our algorithms are loopless, in the sense that the next change can be determined in a constant number of steps, and they can be implemented in hardware. We also give another family of loopless algorithms that is based on the idea of working ahead and saving the work in a buffer
- …