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Conference rusure::math

Title:Mathematics at DEC
Moderator:RUSURE::EDP
Created:Mon Feb 03 1986
Last Modified:Fri Jun 06 1997
Last Successful Update:Fri Jun 06 1997
Number of topics:2083
Total number of notes:14613

726.0. "Partial Vector Reversals" by COMET2::ROBERTS (Dwayne Roberts) Sat Jul 04 1987 00:19

    Given:
    
    an n-element vector V the elements of which are unique and in some
    known but random order; 
    
    a function F(V,x) which returns an n-element vector with the first x
    elements of V reversed and the remaining elements unchanged. 
    
    Can one determine by examination of the initial state of V what the
    least number of applications of the function F would be required to
    return a vector in ascending order? 
    
    For example, assume the initial state of the 5-element vector V is 
    
    V  = 4 1 2 3 5	F(V ,4)=
     0			   0
    
    V  = 3 2 1 4 5	F(V ,3)=
     1			   1
    
    V  = 1 2 3 4 5
     2
    
    In this example, two applications of F were required and is the
    minimum.  Is it possible to look at the initial vector and determine
    that the minimum is 2?  Is there a strategy to get to the ordered
    vector in the least number of "moves"?
    
T.RTitleUserPersonal
Name
DateLines
726.1Looks like funAKQJ10::YARBROUGHWhy is computing so labor intensive?Mon Jul 06 1987 13:052
Interesting question - if an algorithm exists, it would be even more interesting
to see if it could be extended to Rubik's Cube. 
726.2CLT::GILBERTeager like a childMon Jul 06 1987 18:591
   See note 425 -- "Flipping stacked disks".
726.3Question ...726MLCSSE::MILLERSun Nov 29 1987 01:402
      Can I apply a iteration solution in order to minimize redundant
    pertubations or am I limited to analytical solutions?