Feedback and Questions

The checkmark at Exocet doesn't work. The solver used Exocet strategy to solve a puzzle. I removed the checkmark next to Exocet, reloaded the puzzle to see how the solver would solve it without using Exocet, but it did used Exocet anyway.

The button for "Email This Board" gives "This board is empty!" for puzzles where many candidates have been removed but no single cell is solved. (There are such configurations that are solvable and have unique solution.)

The expectation is to still get the state of the board in the text format.

In "Unique Rectangles" it confused me when under subheading "Type 2 Unique Rectangles", second to last sentence you say "8's on brown cells are eliminated." which suggests to me that the 8's in H4 and H6 can be eliminated when it's actually the 8's highlighted in yellow that can be eliminated. Can this be made clearer? Thanks for this website.

Your solver correctly describes this as a BUG Sudoku and gives a solution with D1=6; D3=1; F3=5; D6=5 ;F6=1. This cannot be correct because it allows for an alternate solution with D1=6; D3=5; F3=1; D6=1; F6=5.

The correct solution is based on D3=6 chosen to eliminate the possibility of an alternate solution.

The current jigsaw sudoku for 10/25/2021 has an error in it. A 3 has to be in row A of the yellow piece and a 3 also has to be in row B of the yellow piece. How can this be.

On the home page, I noticed you are using different terms for cells. Sometimes they are called "cells" and other times "squares".
The problem is, other sites have different names for units...some call a 3x3 unit "box", some call it "square", some call it "region". So, when reading the instructions or analysis, it become confusing if you have ever been exposed to other Sudoku sites. Is there any chance you could describe your terminology at the beginning of the explanations? I wish there were a common terminology where everyone had the same unit names in mind.

Also, where are you, where J follows H in the alphabet?

First of all, I just want to say thanks for providing such an amazing piece of software and resources, it's been invaluable to me.

I believe I've found a bit of an inconsistency with the way the solver applies (at least) hidden singles in the solve path. In the sudoku provided, step 10 lists the following hidden singles:

4 found once at r1c2 in row, 4 candidates removed
6 found once at r1c1 in row, 1 candidate removed
8 found once at r9c5 in column/box, 1 candidate removed

The problem is with r1c1: the 6 is only found once in the row because it has been eliminated from r1c2 in the same round. This elimination is therefore not deducible from the state of the board at step 10.

Stepping through the steps manually on the solver separates these steps.

Maybe there is a reason the solve path wants to group these steps, but it seems bizarre to me.

Thanks again

I believe you have a minor bug involving the labeling of shapes in the explanation of "Double Line / Box Reduction". You say "Down the center are two columns where 2 is present in shapes 4 and 5 -- and just those 2 shapes." But this is for "Andrew Stuart 7", and according to the labeling in the lower right corner of the Solver page for this configuration, those shapes are 1 and 2, not 4 and 5.
I have never understood the labeling of shapes in Jigsaw configurations. Judging from the labels for Andrew Stuart 7 and for Cabbage, I believe they are labeled by whim rather than by any systematic procedure. Is that correct? If not, is the rule explained anywhere in your pages?
P.S. Thanks very much for such an incredibly useful reference!

I just love your Sudoku Solver. Thanks a lot !

One small question: I have edited off some possibles in any Sudoku. With the "auto clear" button on, when I enter a solution, the action taken by the solver is not to logically clear out just the values that have to be cleared in that box, row and column because of this new number, but it resets ALL possibilities back. Meaning, my edits are discarded, the possibilities I edited out earlier are set back again. Could there be an option to make a real clearing, not a reset to all possibilities?

This sounds so easy, am I missing something?

Best regards, Theo

Hi Andrew,

Firstly, what a brilliant programme! I have used it a lot over the last 2 years as I've tried to improve my own solving skills. It has helped me improve a lot.

However, on this board I have been able to solve a puzzle that the solver cannot, and I would expect it to be able to. I am wondering why it cannot.

Here's the board:

There is a Killer Sudoku board I would like you to look at

Click on this link:
https://www.sudokuwiki.org/killersudoku.htm?bd=121112211121133441112213122132112111332312322111311321221213311133221121114411121,300622000012002100000000001600040000000025003200191400000600000013000000000000130000151200210000000000000022130000210000000000180500000027001000000008000000000000

When it gets stuck, cells G6, H6, J5, and J6 sum to 13 (by summing columns 7, 8, and 9 and looking at the spill over). 13 in 4 cells in the same block has to contain 1. This means that J4 has to be 2 (the solver gets stuck with J4 being only 1 or 2).

If I set J4 to 2, the solver then solves the puzzle.

Why doesn't the solver see that J4 has to be 2?

I ask for two reasons:

1. The solver seems to solve much harder situations than this one.
2. If you do decide to update the solver again, maybe there's a piece of logic you could insert?

Again - thanks for doing the solver; it's a great tool!

Brent