2. Qe6! is most precise because black can only extend the mating sequence to six moves. However 2. Qe8 will also mate in a longer sequence in which it is possible, however, to go astray and lose. If this were a problem I imagine that would be an unacceptable dual solution, but as it’s from a real game it isn’t really a flaw.
After 1. Qe6+ also technically mates too, since 1. … kh7 2. Qg8+ forces the original position in which 1. Re6 mates. But of course the minimum sequence will then be 8 moves to mate.
1.Rd6+!
1… Kf5
2.Qh7+ loses the Queen
1… Kh5
2.Qe8+ g6
3.Qe2+ g4
4.Qe5+ g5
5.Qe8+ Qg6
6.Qg6#
1.Rd6+
a) 1. … Kf5
2.Qh7+ and wins Queen
b) 1. … Kh5
2. Qe8+ wins Rack or Queen or even matt because
3. g5 (if … Black moves Q or R)or f6+ (if Kg5)
1. Rd6+!
if
1… Kf5
2. Qe6+ mate
and if
1. Kh5
2. Qe8+ g6
3. h3! (if 3. Qe2+ g4 4. Qd5+ Qf5 and now black should save the game)
now if,
3… Qc2
4. g4+ Kh4
5. Qe3!! and the eventual 6. Qg3+ mate cannot be prevented
and if,
3… g4
4. hxg4+
now black has two options
if
4… Kg5
5. Qe3+ Kxg4 (5… Kf5 6. Qf4+ mate)
6. Qf4+ Kh5
7. Qh4+ mate
and if
4… Kxg4
5. Qe2+ Kf5 (5… Kg5 6. f4+ Kf5 7. Qe6+ mate)
6. Qe6+ Kg5
7. f4+ Kh5
8. Qh3+ mate
1. Rd6+ Kh5
2. Qe8+ Kg4
3. f3+ Kf5
4. Qe6#
1.Rd6+ Kh5
2.Qe8+ g6
3.Rxg6! Qxg6
4.g4+
Faster mate by :
1.Rd6! Kh5
[1…Kf5 2.Qe6#]
2.Qe6! g4
3.Qe5+ g5
4.Qe8+ and mate in 2 more moves.
2. Qe6! is most precise because black can only extend the mating sequence to six moves. However 2. Qe8 will also mate in a longer sequence in which it is possible, however, to go astray and lose. If this were a problem I imagine that would be an unacceptable dual solution, but as it’s from a real game it isn’t really a flaw.
After 1. Qe6+ also technically mates too, since 1. … kh7 2. Qg8+ forces the original position in which 1. Re6 mates. But of course the minimum sequence will then be 8 moves to mate.