On May 15, 11:21 am, wrote:
This one is mine:
1. 4k3/qqqqqqqq/8/8/8/8/QQQQQQQQ/4K3 w - - 0 109: [pos. 1]
White to play and mate in 4.
There are no duals - only one moves mates in 4. [there is no mate in 3
or less.]

It would be better - just being a stickler - to note that there is no
dual *in the key*. There are at least 22 duals in the continuation.

Construction of such a problem with no duals at all would be
phenomenal.