# Accessing Brute Force Sieve, 
 # a master program to run the BruteForceSieve procedure
 # Version 1.1
 # Ken W. Smith
 # Begun in May 2006, 
 # Last modified May 14, 2006.

 #     Place this file, and the files 
 #        DifSets.txt,
 #        Lift.txt,
 #        BruteForceSieve_DS.txt
 # in the same directory as the GAP application.  Then run this program.
 #     To run this program, insert the following Read statement
 # gap> Read("AccessingBFS.txt");
 # at gap cursor.

  Read("DifSets.txt");
  Read("Lift.txt");
  Read("BruteForceSieve_DS.txt");

 WriteFile  := "BFS_DS_expand.txt";
 WriteFile2 := "BFS_DS_out.txt";
 PrintTo( WriteFile, "Brute Force Sieve\n\n");
 PrintTo( WriteFile2, "Brute Force Sieve\n\n");

 ############################################################
 # Set up parameters here:  (v1, k, lambda) are design      # 
 # parameters; [v, cn] are group parameters.                #
 # max_chain_holes is the maximum value allowed for         #
 # the difference between the best possible chain length    #
 # and the true chain length of a particular group.         #
 ############################################################
 threshold := 500000; printflag := 1;
 
 SearchSet := [ 211, 212, 213, 214, 215, 216, 217, 218, 219, 220,
 221, 222, 223, 224, 225,                230, 231];

 v:=36;v1:=36;k:=15;lambda:=6;max_chain_holes:=2;SearchSet:=[6,7,8,10,11,12,13,14];
 v:=96;v1:=96;k:=20;lambda:=4;max_chain_holes:=2;SearchSet:=[205];
 
 Starttime00:=Runtime();
 chain_choice := 1;

 multiplier := v1/v;
 for cn in SearchSet do
   Starttime0 := Runtime();
 ############################################################
 # Print header
   Print("\n**************************************************\n");
   Print("* Working on Small Group [", v, ", ", cn, "]...             *\n");
   Print( "**************************************************\n");
   AppendTo(WriteFile, "\nWorking on Small Group [", v, ", ", cn, "]... \n");
   AppendTo(WriteFile2, "\nWorking on Small Group [", v, ", ", cn, "]... \n");
 ############################################################

   max_chain_list := MaxChains( SubgroupIncidenceMatrix(v,cn) );
   chain := max_chain_list[ chain_choice ];

# Let's try to improve our choice of chains:
   g := SmallGroup(v,cn); ns := NormalSubgroups(g);
   for c in max_chain_list do if Size( ns[c[2]] )=2 then chain := ShallowCopy(c); fi;od;
   for c in max_chain_list do if Size( ns[c[3]] )=4 then chain := ShallowCopy(c); fi;od;
   for c in max_chain_list do if Size( ns[c[4]] )=8 then chain := ShallowCopy(c); fi;od;
#   for c in max_chain_list do if Size( ns[c[5]] )=16 then chain := ShallowCopy(c); fi;od;
#   for c in max_chain_list do if Size( ns[c[6]] )=32 then chain := ShallowCopy(c); fi;od;
 
   chain_size := Size(chain);
 
 # The complexity of this program depends on the length of the
 # the normal subgroup chain.  We'd like it to be as long as 
 # possible.  'max_chain_holes', normally set to zero, 
 # determines the number of gaps allowed in the subgroup chain.
 # The best possible is when the chain length is the same as 
 # the number of factors of v.
   if chain_size +  max_chain_holes >= Size(Factors(v))+1 then 

   Print("chain size is ", chain_size,"\nchain is: ", chain,"\n");

   ############################################################
   # BruteForceSieve( [v,cn], [v1,k,lambda], chain, threshold, printflag, WriteFile )    #
   ############################################################
   PostSolution :=  BruteForceSieve_DS([v,cn], [v1,k,lambda], chain, threshold, printflag, WriteFile);

    ############################################################
    # Print results
   Print("There are ", Size(PostSolution), " difference sets: \n", PostSolution,"\n");  
   AppendTo( WriteFile, "There are ", Size(PostSolution), " difference sets: \n", PostSolution,"\n"); 
   AppendTo( WriteFile2, "There are ", Size(PostSolution), " difference sets: \n", PostSolution,"\n"); 

   fi; # if Size(chain) ...

   Print("Run time for this group was ", QuoInt( Runtime()-Starttime0, 60000 ), " mins. \n");
 od; # for cn in SearchSet...

 Print("Run time for the entire search was ", QuoInt( Runtime()-Starttime00, 60000 ), " mins. \n");