# Direct Confrontation

Direct Confrontation is a tie breaker which breaks ties by considering the games between players in the tied group. Similar to Direct Comparison, but without the requirement that all in-group games have been played. Abbreviated DC (confusingly, as Direct Comparison is also abbreviated as such).

## Algorithm

Implemented in the OpenGotha tournament directing software, the OpenGotha manual describes it as follows:

Direct Confrontation. This performs a special sort of players who have the same score for higher priority parameters than DC (For example: MMS or SOS), so that a player is above the ones he has defeated. DC numeric value has no meaning by itself, it is set to enforce rank given by following algorithm:

• This applies to a group of players who are equal according to higher priority parameters, looking only at results of games played against each other.
• It detects and removes cycles of victories, by putting players forming a cycle in a single "node" sharing all victories and defeats against other players of the group.
• Considering all players with no victory against the group, take the one (or the ones, there can be ties) with the lowest score for parameters after DC. Rank this player last.
• Remove ranked player from the group and iterate previous step.

An implementation of the algorithm used can be found in this code

## Example

Used in the 2010 Shusaku cup, here are place 7 through 14 from that event:

``` #                       Rank   Club Pt                                           MMS  DC SOS-1 Rating
7  Burzo Cornel          6D RO BaMa 3 18+/b0  4-/w0 12+/b0  3-/w0  9+/b0  1-/b0  37   7   190  562
8  Simara Jan            6D CZ KaVa 3  3-/w0 23+/b0 15-/w0 10+/b0 16+/w0  4-/b0  37   6   185  523
9  Zhurakovskyj Bohdan   5D UA Rivn 3 15-/b0 22+/w0 10+/w0  4-/b0  7-/w0 18+/b0  37   5   184  432
10  Florescu Ion          6D RO Pits 3  1-/b0 13+/w0  9-/b0  8-/w0 19+/b0 17+/w0  37   4   187  561
11  Jabarin Ali           5D IL TAv  3  4-/w0 16+/b0  6-/b0 18+/w0 13+/b0  5-/w0  37   3   187  457
12  Lin Viktor            5D AT Gote 3  5-/w0 14+/b0  7-/w0 19+/w0 15+/b0  6-/b0  37   2   186  446
13  Corlan Lucian         5D RO Bucu 3  6-/w0 10-/b0 24+/w0 25+/b0 11-/w0 15+/b0  37   1   183  428
14  Serban Mihai_Valentin 4D RO Bist 4 19+/w0 12-/w0 30+/b0  5-/b0 22+/b0 16+/w0  37   0   182  349
```

Given the list of results, we repeatedly apply the above algorithm:

First iterarion
Burzo, Simara, Zhurakovskyj, Florescu, Jabarin and Lin all defeated at least one player in the group so should not be last. Corlan and Serban have not. So either Corlan or Serban is last. Serban has lowest SOS, so Serban gets last place (DC 0).
Second iteration
With Serban removed, Burzo, Simara, Zhurakovskyj, Florescu, Jabarin have all beaten one of the others. Lin and Corlan have not (Lin's victory against Serban no longer counts). Corlan has lowest SOS, so Corlan is out next (DC 1)
Third iteration
Burzo, Simara and Zhurakovskyj have all beaten one of the other players. Florescu, Jabarin and Lin have not (now that Corlan was dropped). Lin has worst SOS, so Lin is out next (DC 2).
Fourth iteration
Burzo, Simara and Zhurakovskyj have all beaten one of the other players. Florescu and Jabarin have not. Flor and Jabarin have same SOS. Jabarin is dropped on Rating (last column) (DC 3)
Fifth iteration
Burzo, Simara and Zhurakovskyj have all beaten one of the other players. Florescu is droppen next (DC 4)
Sixth iteration
Burzo has beaten one of the others, Simara and Zhurakovskyj have not. Zhurakovskyj is dropped on SOS (DC 5)
Seventh iteration
Neither player has beaten the other. Simara is dropped on SOS (DC 6), Burzo remains and gets first place (DC 7)