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

- - - - - - - - - - - - - - - - - - - - - - Version 2.3 - 8/22/17 - - - - - - - - - - - - - - - - - - - - - -

In this release, the Create Action has been changed to use a background/foreground approach.

Puzzles are created in the background at a rate of several per second. The puzzle that best meets the user's target of strategy and star level, as well as clue pattern if one is defined, is displayed in the foreground. The following screenshots show you how this works:

target50%.png (27.42 KiB) Viewed 103 times

The above screenshot of the Random action popup shows how you choose the strategy level and difficulty level (star level) that you want the puzzle to have. In this case, suppose that we select "Hard***". Note that we have indicated a maximum of 1200 puzzles to be created.

This next screenshot was taken while the background process is executing. All the Create screen buttons have been hidden, and a "Select" button added. At first, you will see several puzzles in close sequence as the process targets in on the designated strategy and star level. Once there, it will use other Grader statistics to judge the quality of a puzzle, the most important one being the number of strategies successfully applied. Several applications of easier strategies will outrank a smaller number of more difficult strategies.

Before long, the period between the "best" puzzle and the next "better" puzzle gets longer, and you will see something like the following. You only know something is going on because the "Processing" number is continually increasing:
Last "best" puzzle
hard3star50%.png (18.13 KiB) Viewed 103 times

But this gives you a chance to look at the Grader statistics. In this case, we see that the 147th puzzle had a line-block intersection, a couple of Xwings, a Ywing and a XYZwing. If you like what you see, you can touch "Select" and you will return to the full Create screen, where you can choose to go ahead and solve the puzzle. If you do not touch "Select", you will return when the maximum of 1200 puzzles is reached.

The pattern used here (which is nothing more than part of a puzzle manually entered into a "protected area") leaves plenty of cells for Random to use. The screenshot in the App store for this release uses a geometric pattern of cells for Random to use, but it is not too restrictive as the pattern has more cells than necessary. In that case, when return is made to the full foreground Create screen, the user can manually add clues to the pattern (or invoke Random again with the default option to do the same for each empty cell). If you are interested solely in creating a pattern puzzle, then the default option (no grade level specified) is a good choice.

Creating Extreme**** puzzles can be slow, as the Grader has to try every strategy it has available before giving up (which is what makes it a 4-star puzzle). But if you are interested in creating one of these difficult-to-solve puzzles, you might want to turn off the option that causes Random to distribute clues evenly between units. The most difficult 4-star puzzle in the library was rated by Andrew Stuart's grader to be over 900. This was a couple of years ago, before that distribution algorithm was implemented, when Random was truly random. Not sure whether that is generally true, but it might be worth experimenting.

Found this puzzle (now graded 861) and posted it it on the Puzzles board. See Extreme 8/30/17

- - - - - - - - - - - - - - - - - - - - - - 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.

If you had turned on the option that displays grader statistics, you will see them along with the displayed Grader levels. Particularly at the Basic and Moderate levels, the abbreviations and counts you see may be different from the strategies you end up using because the Grader may apply them in a different order. But it will give you a general idea of what strategies are required.

Note the "Create Protect Pattern" button on the Import screen. This causes a pattern of cells to be generated from the imported puzzle that Random should not use when creating a puzzle. You can then Clear the puzzle and you have a pattern that you can use to create other puzzles.

The primary motivation behind this button was not to give you the ability to lift patterns from other peoples puzzles. Instead, it was intended to give you the ability to create a catalog of patterns that you have created from your own puzzles.

You generate a pattern using the Protect Cell or Block buttons in the Create screen. These can be used to select and color those cells that Random should not use (or you can use the Protect Cell button to select only cells that Random CAN use and then press the Invert button when done). Once you have done that, you can create any puzzle using Random. When you select Solve, you can export the puzzle using the Export button. You then paste the 81 characters in the pasteboard in any text file you have created, along with some name you have given that pattern. You need only to select that puzzle, copy it and Import it to recreate the pattern for Create.
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