Not sure if this is correct, but I have Xavier as the answer.
I changed the names to letters as follows:
Zorba – a (17 times)
Yolanda – b (15 times)
Xavier – C (10 times)
Number of games played = (10 + 15 + 17) / 2 = 21 matches
I just tried to make it work by starting with a vs b in the first match and ended up with this run of matches:
Match Player 1 Player 2 (Loser)
1 a vs b (b)
2 a vs c (c)
3 a vs b (b)
4 a vs c (c)
5 a vs b (a)
6 b vs c (c)
7 a vs b (a)
8 b vs c (c)
9 a vs b (a)
10 b vs c (c)
11 a vs b (a)
12 b vs c (c)
13 a vs b (b)
14 a vs c (c)
15 a vs b (b)
16 a vs c (c)
17 a vs b (b)
18 a vs c (c)
19 a vs b (b)
20 a vs c (c)
21 a vs b
Looking at the problem, I’d be suprised there aren’t more solutions to this. So I’m not sure my answer is always right.
Ian