USOpen97 – xtab cross contamination

<Phony> found a problem with <Carl Boor>, who appears to mostly play D5’s (i.e. 5-Day schedule players). But in R7 he plays <Aleks Wojtkiewicz>, a solid BP (i.e. Busy Person, those given R1-6 byes).

<Phony> was kind enough to provide the xtab index number, 173, of <Boor>. So let’s see who he played.

 >>> score(173)

173. Carl Boor  (1959)      6.5 / 12    ( +6 =1 -5 )

    1    1.0   W   446   Eamus Jr, D J                    1192    0.0
    2    1.0   L    15   Ardaman, Miles F                 2438    2.0
    3    2.0   W   209   Grabowski, Craig                 1499    1.0
    4    3.0   W   230   Hall, Ashley                        0    2.0
    5    4.0   W    71   Musgrove, Charles W              2175    3.0
    6    4.5   D   122   Kahane, Gabe                     2103    4.5
    7    4.5   L     7   Wojtkiewicz, Aleks               2690    5.0
    8    4.5   L    78   Mayer, Scott                     2071    5.5
    9    4.5   L   111   Bass, Charles William            2123    5.5
   10    4.5   L   145   Le Grand, Michael                1633    5.5
   11    5.5   W   309   Traldi, Oliver                   1604    4.5
   12    6.5   W   307   Bedford, Frederick R             1526    5.5

Final rating: 1959  (+0)      Average Opp Rating: 1879

The question involves R7, where Boor played <Aleks Wojtkiewicz> (shown in red above). Let’s see who Wojtkiewicz played:

>>> score(7)

7. Aleks Wojtkiewicz  (2690)      9.0 / 12    ( +7 =4 -1 )

    1    0.5   H     -   Bye
    2    1.0   H     -   Bye
    3    1.5   H     -   Bye
    4    2.0   H     -   Bye
    5    3.0   B     -   Bye
    6    4.0   B     -   Bye
    7    5.0   W   173   Boor, Carl                       1959    4.5
    8    6.0   W    46   Gibson, Franklyn E               2206    5.0
    9    7.0   W    33   Ruppert, Artem Edmund            2112    6.5
   10    7.0   L     4   Garcia, Gildardo                 2577    8.5
   11    8.0   W    40   Cunningham, Walter               2270    7.5
   12    9.0   W    35   Vucic, Mladen                    2429    8.0

Final rating: 2686  (-4)      Average Opp Rating: 2258

Now, the first six rounds being byes puts Wojtkiewicz solidly in the BP group, who played R7-R12 from Sun-Fri (Aug 10-15). Let’s assume so for the moment, and recheck later.

For the moment, let’s return to <Boor>. His R1 opponent is <Eamus>, who I recognize as a triple entry, that I marked off already:

>>> Eamus
 [446, 524, 532]

The first entry is the “official” 12-round entry. According to <Phony>, Eamus was a BB-er (Best Ball, i.e. EB/TR R1-6, pick best score), who dropped both to reenter as D5. Playing Eamus in R1 strongly suggests Boor was also a D5-er. Let’s check this assumption with my group() function.

For this function to work properly, certain special cases of known “cross contamination” must be excluded. These are players who we already know played a game or two in sections other than their main section. Let’s enumerate the cases I know about presently:

>>> exclude_list
 [42, 365, 314, 293, 201, 516]
>>> for e in exclude_list: print " %3d  %s" % ( e, norm( M[e].name ) )

  42  Neff, Elliott
 365  Neff, Dr Robert
 314  Neff, Ethan
 293  Neff, Raphael
 201  Wagner, Joseph
 516  Bowen, Donald E

I use an auxiliary function, norm(), to print the normalized names (i.e. surname,prenom).  The xtab structure, M, is indexed via the USCF xtab index. Anyways, the main point is that we might have to add another case to this list.

Continuing on, here are the results for Boor’s opponents:

>>> for x in M[173].X[:8]: group( x[1] )[0]

 10
 10
 10
 10
 10
 10
 7
 10

>>> M[10]
Alexandr V Reprintsev   2529 (12651570)   9.0

The idea is loop over Boor (173)’s opponents in the first eight rounds (i.e. the M[173].X[:8]). Then we see if these opponents belong to the same “group” or section in the tournament. A group is just a selection of players who form a subgroup within the tournament, only playing each other during the first four rounds (four by default).

We see that all of Boor’s opponents in each round, except R7, belong in Reprintsev’s group. Reprintsev is recognized as the best D5 player.

We can’t do the same for Wojtkiewicz, if he were a BP-er, since he didn’t play in the early rounds (which is why he goes into a group all by himself). Well, we can check his R8 opponent, to ensure it’s not a D5-er.  Let’s do that, for <Franklyn E Gibson>

>>> M[46]
Franklyn E Gibson   2206 (12535252)   8.0

>>> group(46)[0]
10

>>> len( group(46) )
151

Whoa, what is this?! Wojtiewicz looks to play two D5-ers during his R7,8 rounds. Which suggests he was a BP who couldn’t make it on Sunday, so maybe the tournament organizers allowed him to rejoin the tournament stream via the D5 group. A little suspect on several levels, maybe, but that’s what the data suggests.

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