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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

840.0. "Lock traffic" by ELWD2::CHINNASWAMY () Tue Mar 08 1988 16:53

 I get the following information from VPA and Monitor (?)

+-------------------------------------------------------------------+
| The following table gives a summary of the average amount of lock |
| traffic per second in the cluster.                                |
+-------------------------------------------------------------------+

               Local      Incoming     Outgoing   
    Node    ENQ/CVT/DEQ  ENQ/CVT/DEQ  ENQ/CVT/DEQ
  --------  -----------  -----------  -----------  
  MELODY      3/  3/  3    2/  3/  2    1/  2/  1 
  PISCES      7/  8/  7   16/ 15/ 16    0/  1/  0 
  GUMDRP     20/ 33/ 20    0/  0/  0   15/ 11/ 15 
  FORNOW      0/  0/  0    0/  0/  0    0/  1/  0

 I once tried to find out the actual traffic from any node to other nodes.
 For instance, Melody has two incoming ENQs and 1 outgoing ENQs. Where are
 they coming from and where is it going to? I tried to generalize this for
 N nodes. I did not spend too much time on it. I gave up thinking that not
 enough information is available to solve the problem. Did any one solve this
 problem?

Swamy

T.RTitleUserPersonal
Name
DateLines
840.1but I digressZFC::DERAMOI voted on Super Tuesday!Tue Mar 08 1988 22:539
    That reminds me of a [a) similar b) totally unrelated] problem.
    The NFL standings were in the newspaper two weeks into the
    season, with the won-loss and points for-against totals for
    each team.  I also had a schedule so I knew who had played whom.
    
    I never did figure out if this was enough information to derive
    the score of each game.
    
    Dan
840.2CLT::GILBERTWed Mar 09 1988 12:308
    Suppose we have 3 nodes: A, B, and C, with i arcs between A and B,
    j arcs between A and C, and k arcs between B and C.  We are given
    i+j (arity of A), i+k (arity of B), and j+k (arity of C), and want
    to determine i, j, and k.  That gives 3 equations in 3 unknowns.

    Suppose we have 4 nodes.  We get 4 equations in 6 unknowns.

    Suppose we have n nodes.  We get n equations in n(n-1)/2 unknowns.
840.3ZFC::DERAMOThink of it as evolution in action.Wed Mar 09 1988 12:594
    But the fact that the solutions are limited to nonnegative integers
    gives more constraints than just "n equations in n(n-1)/2 unknowns."
    
    So maybe some n=4 cases can be solved, too. (-:
840.4TLE::BRETTWed Mar 09 1988 16:3917
    Consider the trivial case,
    
              outgoing                  incoming
    
    		A			  C
    
    		B                         D
                                           
    
    Now, if A and B each have one out-going link, and C and D each have
    two incoming links, there is (obviously) no way of determining
    whether (AC, BD) or (AD, BC) was the actual pattern.
    
    Since you can't solve the simple case...
    
    
    /Bevin