Tutorial 6 - Logic using Auto-completion (Advanced)

This tutorial is a quick start to editing logic similar to tutorial 4. It uses the [Draw Logic as Truths, Auto] mode to find logic in a puzzle that has several logic structures that eliminate multiple candidates. See tutorial 1 for more detailed examples of editing options.

The [Draw Logic as Truths, Auto] mode is the same as the [Draw Logic as Truths] mode except Xsudo will auto complete links when truths are entered. If the logic detects eliminations or assignments, it will automatically remove links not required for the eliminations/assignments. After the first eliminations appear, Xsudo continues to analyze as additional logic is entered however, only links that contribute to eliminations and assignments will be displayed.

On startup, the currently selected puzzle file is xsudon.sud, which is the default puzzle file. This file contains the tutorials and a few other interesting examples. This file is normally used as a working or scratch pad file and cannot be erased.

Open the Tutorial 6 Puzzle

· Click the right tab of the puzzle list in the toolbar.............

· Scroll up and click on the puzzle called Tutorial 6.

· Click on the load puzzle icon  to the right.

Tutorial 6

Tutorial 6 will enter and analyze the following logic, posted in a recent forum. The logic has two parts, a root part containing a hidden quad, and two logic parts, A and B, that are added to the root. Candidates and cells used in this tutorial are highlighted with a light shaded color (cells) or a small black 'X' to the upper right (candidates).

Hidden quad c2 : 1356r5789c2=8r9c2-8r9c1=8r2c1-8r2c5=(8-5)r1c4=(5-9)r9c4=9r8c4-(9=7)r8c8

A. -7r9c8=(7-8)r9c1=8r9c2 : loop=><8>r2c2 <6>r1c4 <13>r9c4 <345>r9c1

B. -(7=3)r8c1-(35=1)r9c3-(13=6)r8c2-(6=5)r7c2 :=><5>r12c2 :=>pointing 5s b1r2 : =><5>r2c58

Go to the [XSUDO] main menu and select [Draw Logic as Truths, Auto], for the auto mode.

For viewing comfort, go to the [Styles] menu and select [Light Assigned Values].

For viewing comfort, go to the [LogicView] menu and select [Default (nice) Styles].

Hidden Quad in c2. The cells of the hidden quad in column 2 are highlighted light yellow. To enter the logic sequentially left mouse click any two candidates in each cell. After entry, the cells will be connected by all possible links.

Root Part. The rest of the root logic can be entered by sequentially left mouse clicking the following pairs of candidates marked 'x' in their respective row/column/box. (8) in c1, (8) in b2, (5) in c4. Note that the first elimination 5<>r9c1 appears. Now complete the root by clicking the marked pair (9) in c4 and clicking the two candidates (79) in r8c8. No more links appear because there are no new eliminations. The root is complete.

Add Block A. Add Block A to the root by clicking the marked pair. (7) in r9. Additional links appear along with 7 eliminations. This makes a 6 (strong set) rank 0 loop that does not use the hidden quad in c2. The strong link [8r9c1=8r9c2] is also not required.

Remove Block A. Remove Block A from the root by again clicking the marked pair. (7) in r9.

Add Block B. Add Block B to the root by clicking any 2 candidates in each of the two pale blue highlighted cells r8c1 and r9c3. There should now be 9 eliminations and the hidden pair in c2 has been linked into the logic.

Option, for a cleaner view, you can (permanantly) clear the cell highlights with [Execute] menu and click [Clear Cell Markings].

Remove Cell r5c2. Remove cell r5c2 from the hidden quad in c2 to see the effect (click any 2 candidates in the cell). Note that the elimination 5<>r2c2 disappears but the elimination 5<>r1c2 remains. Why??

Answer. To see why, go to the [Set Viewing] menu and click [Black Rank 0 Links]. You will see that some links are rank 0 (light black) and some are not. Candidate 5<>r1c2 is removed by the overlap of two rank 1 links. Now re-enter cell r5c2 into the hidden quad. The link in 5c2 is now rank 0 and eliminates both 5<>r12c2. The rank 1 row link in 5r1 has disappeared.

For detailed examples on editing modes and manual editing see Tutorial 1.