Simon is so nice and fun to watch, but as I’ve gotten better at spotting stuff, he can get frustrating. Pencil Mark is way better at scanning.
I plugged your puzzle into sudoku.coach (you can import from a picture) and it has more than one solution.
Yes he will sometimes miss a naked single while working out a swordfish or something.
I do recall with the old Sudoku app I was using previously (which no longer works properly in a newer iOS), it was basically “teaching” me as I went along. And it was clearly leaning on bifurcation, because one of the things it would often mention for a hint was along the lines of, “Since having these numbers here would mean there is more than one solution, that can’t be correct, therefore they have to go here instead.”
Thank you!
I’d looked at this puzzle for a long time but still had the suspicion that I’d share it and within a minute someone would post “You do know you have three 8s on one row, right?”
Which numbers are the ones you filled in? The red ones or the dark ones?
You’re assuming that the answers filled in up to this point are correct. They could be incorrect without violating the constraints.
I just entered only the black ones and that Coach site still says Number of Solutions >1. Someone else can try entering all the red ones.
I think the dark ones are the ones I filled in
If the numbers entered don’t violate constraints and they lead to more than one solution then there was always more than one solution.
Edit: To put it another way, the definition of an incorrect answer is that it leads to a contradiction. Incorrect answers can’t lead to a valid solution.
It seems to be a form of Reductio ad absurdum.
True but I think unlikely; there were no guesses, Id only filled in what I knew from deduction. Of course it’s possible that I made a visual error though.
Thank you. I didn’t think that through.