Recent Changes to the iPad App "Sudoku Fundamentals"

Programs which generate, solve, and analyze Sudoku puzzles

Recent Changes to the iPad App "Sudoku Fundamentals"

Postby nedBlake » Sat Aug 26, 2017 3:42 pm

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Replacement of the Basic Library:

Most of the Basic library puzzles have been replaced, so that all three Basic levels can now be solved without making notes of possible solutions.

The following two images show the Basic range. Underneath each are statistics of what the Grader needed to do and what it needed to find in order to solve the puzzle.

Basic 1 and 3 star.png
Basic 1 and 3 star.png (66.87 KiB) Viewed 451 times

All puzzles are solved by first finding unit singles, followed by finding naked singles when all except 2 or 3 empty cells remain in the unit. These unit singles are reported by the Grader as either block singles or line singles (row or column singles) that it found by looking at intersections by the other two units.

These are called “unit” instead of “hidden” singles, because they represent the single possible solution found in a unit, which may be a naked single.

At the 1-star level, only block unit singles detection is necessary, and naked singles were looked for only when 2 empty cells remain in the unit. These naked singles are very easily found in 1-star puzzles; note the number (nSings) of them found by the Grader versus the unit singles (blkSings).

In the 3-star puzzle, the Grader needed to find several line singles, with many more unit checks needed to solve the puzzle.

The last Grader statistic (maxNSeq) is the longest sequence of naked singles found. This is made as small as possible, so that finding naked singles is distributed more evenly. This rewards one during the solution process, rather than finding these singles all in a clump at the end of the solution.

The first three puzzles in the Basic library are 1-, 2-, and 3-star puzzles that include the two puzzles displayed here.

The Grader statistics give you a general idea of what to expect in a puzzle. Find out what you like (or don’t like) by looking at them after you solve a puzzle, not only for these library puzzles, but also for puzzles you have Imported, or copied from newspapers using the Create action. Then when you use the Random action to create your own puzzles, you have an idea of what to specify and which puzzle to Select or avoid when they are displayed by Create’s Random action .

Rewrite of the Basic Topic:

In line with the above, the first topic in the Fundamentals, “Rows and Columns Crossing Blocks” has been rewritten with the new Sudoku puzzle solver in mind. An interactive display lets the user solve an example that includes all the basic strategies, showing how they relate to the rules of Sudoku. And for more fun, the user also learns how to “preselect” a solution in the keypad for entering in multiple cells (particularly useful for Basic puzzles).

New Export Option:

When solving a puzzle, the user is now given an option to export the input puzzle. The user might choose this option to send the 81-character string to someone, or to import it and use its pattern to Create a puzzle using that pattern.

Add Imported Puzzle to Library:

If the user has turned off the option that allows libraries to be updated when the App is updated (implying that the user is doing the updating), then when a puzzle is imported, an action is provided allowing the user to add the puzzle to its library. Since the puzzle might have been one exported from that library, the add is not allowed and the user gets a message instead if a duplicate is found in the library.

- - - - - - - - - - - - - - - - - - - - - - About Sudoku Fundamentals - - - - - - - - - - - - - - - - - - - - - -

The description of Sudoku Fundamentals in the App store gives you a full description of this App along with screenshots.

But the following may be of particular interest to viewers of this forum:

You can copy the textual image of a puzzle in the Puzzles forum board and then use the Import action to display the puzzle. You have to use the iPad copy mechanism to do this, but you can be pretty sloppy. You can start the copy anywhere before the puzzle as long as there are no numbers or periods in the selected area before you get to the puzzle. You can continue the select anywhere beyond the puzzle. Import will extract the first 81 numbers and periods from the selected text (or less if there are less than 81).

The Import action will send this string to the solver. If a valid puzzle, it will then send it to the grader (which will tell you the strategy level and star level). If the puzzle is not valid (or even if it is valid and you select a cell in the puzzle grid) you will see the Create screen which allows you to edit the puzzle.

The Import action also gives you a "Create Protect Pattern" button You can then Clear the puzzle and you have a pattern that you can use to create other puzzles.
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Re: Recent Changes to the iPad App "Sudoku Fundamentals"

Postby nedBlake » Sun Nov 26, 2017 7:35 pm

This App had a major update on 11/21/17, and the referenced post was edited a few days later.

The update consisted of an almost total replacement of the Basic library. These puzzles can all now be solved without using notes of possible solutions.

I was not thinking only of Sudoku solver beginners, but also the many solvers that prefer this level of puzzle. And believe it or not, I can now see now why they do after solving many of them myself.

This was a big change for me, who originally wrote this App thinking that the ability to draw an implication chain with your finger on an iPad screen would make it popular. I now get the feeling that chains give most Sudoku solvers a headache.

I am beginning to see why solving Basic Sudoku’s is addictive, and I feel some of this addiction myself. I don’t feel that solving these puzzles is necessarily easy. I won’t admit how long it took me to solve the heart-shaped puzzle in the referenced post, but I know it was probably a lot longer than the person I sometimes see in a waiting room going through a book of Sudoku puzzles would take to solve it.

Anyway, I think these puzzles compare well against puzzles I copied and solved from local newspapers, at least when you compare their relative grader statistics.
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