Basic Hanson Homework


This post follows up on sysudokie homework comparing Bob Hanson’s basic solving with Sysudoku basic.

In Sysudoku-ville, Bob’s illustrative puzzle of the last post doesn’t escape line marking. The Hanson 1 BM traceleft over hidden single N5 shows up where expected. No doubt you found the eliminations for 1: NWm => NEm at the very beginning of box marking, and 9: Wm => Cm at the very end. Except that 6: Nm => C6 had intervened to make it 9:Wm =>C9.

Hanson 1 boxed gridThe grid after box marking reveals four more hidden singles.

Having seen the completion grid of the last post, students of human engineering can dig the relatively small number of candidates on the grid at any one time.

But computer solving is different. A horde of candidates is no distraction for Student Assistant.

There was one more naked pair in box marking. SWr8np27.

Hanson 1 LM traceLine marking was moder- ately difficult, Hanson 1 hs gridwith 7 lines of five free cells before the collapse.

A hidden single appeared on the grid. You might look at how it arises in Hanson’s marking.

Two naked triples come up in columns 2 and 7,

 

Hanson 1 nt237the latter triggering an interesting boxline leading to the collapse.

The challenge of the collapse is that it occurs with five lines unfilled. Be very careful to mark bv and convert eliminations to clues only on marked lines. It is low hanging fruit, but there are briars.

In case you want to retrace your steps, I include the 2-D trace of the last long leg of the collapse, picking up on the left where the previous trace ended on the right.

Hanson 2 collapse traceNext time we continue the review by attending professor Hanson’s class on locked sets. Don’t be late!

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About Sudent

My real name is John Welch. I'm a happily married, retired professor (computer engineering), timeshare traveling, marathon running father of 3 wonderful daughters and granddad to 7 fabulous grandchildren. The blog is about Sudoku solving. It covers how to start, basic solving to find candidates efficiently, and advanced solving methods in an efficient order of battle. It is about human solving methods, not computer solving.
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2 Responses to Basic Hanson Homework

  1. Martyna says:

    I like to look down the first three boxes and see if any two boxes have the same nebmur. If so, I take the third box and try to find where to place that nebmur that both of the other two boxes have. < Confusing =S Sorry . OR just look down the full line and see which lines need which nebmurs. Helps a lot!!

    • Sudent says:

      It’s not confusing, Martyna. It’s the most fundamental move in box marking, the Sysudoku way of starting. My full name for it is “double line exclusion”. My short name for it is “dublex”. Start at the beginning.

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