Recently I had the problem of having a very small section.
[code]SwissSys Wall Chart. Purity Spring Open: Open
Name/Rtng/ID St/Tm Rd 1 Rd 2 Rd 3
1 GM Alexander Ivanov MA B 3 W 2 B 4
2611 12513936 1 2 3
2 Patrick R Sciacca NH W 4 B 1 bye
2119 11235611 ½ ½ 1½
3 John P Elmore NH W 1 bye B 5
1984 12747422 0 1 2
4 Nathan A Smith NH B 2 W 5 W 1
1983 12824896 ½ 1½ 1½
5 Albert French Jr NH bye B 4 W 3
1839 12483576 1 1 1 [/code]
The problem is that Mr. French withdrew after the third round. Any ideas on how to pair the fourth? If it matters, there are three place prizes in the section.
Notice the 1 needs white for equalization, 4 needs black for equalization and 2 and 3 are due white for alternation (3 being more due because of having the most recent black)
Options:
A) pair by score and equalize colors (assuming once 27A1 is broken it doesn’t matter how often it is broken - so you may as well pair the tournament leaders)
1-3 (3 plays 1 twice with alternating colors, and 3 never plays 2 or 4)
2-4 (2 and 4 play each other twice with 4 having black both times)
B) minimize repairing with two players replaying (obeying 27A1 as much as possible)
1-2 (only game where the players replay, with 2 having black in both games)
3-4
C) as B but do not repeat color/opponent combinations (there is no reference to such an avoidance)
1-4 (requires a 136 point transposition to avoid a color&opponent repeat and the players still end up playing the same colors as in B)
3-2
D) convert it to a five-player round robin with 1, 2 and 4 getting forfeit wins over 5 (requires time to get two successive games in for player 3)
round 4 has 3-2 (or toss for colors)
round 5 has 4-3 (or 3 is black if white in round 4 and otherwise toss for colors)
This gives Ivanov first and the other places are determined entirely by the 2-3-4 round robin.
Many would-be TDs, and for that matter many current TDs, just let a pairing program make the pairings. The interesting questions in the forums are from fairly rare circumstances that many TDs will never encounter.
Also, remember that there are often multiple legal ways of pairing a section. An old comment is that 10 NTDs will pair the same round 10 different ways and all 10 ways will be valid.