A repeated movement of a piece between two squares a and b. No less than three moves are required.
Hegermann, Bernard
The Problemist FCS, 1934
1.Kxh8
Kh1
2.Kg8
Kg1
3.Kf8
Kh1
4.Ke8
Kg1
5.Kd8
Kh1
6.Kc7
Kg1
7.Kd6
Kh1
8.Kxe6
Kg1
9.Kf6
Kh1
10.Kg5
Kg1
11.Kf4
Kh1
12.Kxe4
Kg1
13.Kd4
Kh1
14.Kc3
Kg1
15.Kxb3
Kh1
16.Kxb4
Kg1
17.Kxb5
Kh1
18.Kc4
Kg1
19.b5
Kh1
20.b4
Kg1
21.b3
Kh1
22.b2
Kg1
23.b1=Q
Kh1
24.Qf5
Kg1
25.Qf7
gxf7
26.Kc3
f8=Q
27.Kd2
Qc8
28.Ke1
Qc1#
Krampis, Illo
Die Schwalbe, 2019
1.Qxh1
Ra8
2.Qxa8
a7
3.Qh1
a8=Q
4.Qe1
Qf3#
Semenenko, Valery
Die Schwalbe, 2018
1...Bxh8
2.Ke7
Ba1
3.Qb2+
Kd3
4.Qh8
Ke4
5.Qe8
Bh8
6.Bh6
Ke5
7.Bf8
Bf6#
Abdurahmanović, Fadil
Die Schwalbe, 2010
1st Prize
1.Be6
Kd1
2.Qe5
Ke2
3.Kf5+
Kf3
4.Bb3
Bc4
5.f6
Bg8
6.Be6
Bh7#
Martin Anton, Luis Miguel
feenschach, 2012
1.Be3
Re1
2.Bc1
Re8
3.Be3
Re1
4.Bc1
R1e7#
Semenenko, Oleksandr
A. Feoktistov-70 JT, 2018
1st HM
1...Sa7
2.Ra8
Sc8
3.Ra4
Sa7
4.Ra8
Sc8
5.R8a6
Sa7
6.Ka5
Sc6#