Hi.
I have a question of nomenclature. Is there a name given for a particular
set of 4 cells from an otherwise empty 4x4 grid, having the property that
they include ONE cell in each row, ONE cell in each column, and ONE cell
in each of the two main diagonals?
An example:
╔════╤════╤════╤════╗
║ ▓▓ │ │ │ ║
╟────┼────┼────┼────╢
║ │ │ ▓▓ │ ║
╟────┼────┼────┼────╢
║ │ │ │ ▓▓ ║
╟────┼────┼────┼────╢
║ │ ▓▓ │ │ ║
╚════╧════╧════╧════╝
I hope the above figure shows up well in your display. You may wish to
copy all
