Another test of your Sysudoku Basic, and another witness that the PencilPress Extreme collection is basic level. On the other hand, that doesn’t make it dull. The bypass is actually a worthy challenge, but you have to experience it to know. Here is the bypass of the PencilPress Extreme bottom right 33.

Copy the givens from last post and make the moves, explaining how the obscure ones work. The walkthrough of Sysudoku basic in the Guide includes trace reading, but you can interpret it just by taking it as saying what you would do next.  If you really can’t follow it, there’s a page that lays out in detail the plan and structure of Sysudoku traces.

Now compare your bypass grid on Tom Sheldon’s Master Class 40 with this one.  Looking back, was the 3-fill 258 in r5  available in r5 when E17 was added? The trace can tell us.

In the bypass trace below, we look at the positions of C3 and C6, relative to E17.

C3 was placed earlier than E17, but C6 comes later. E17 made r5 a 4-fill. Going down the near collapse, C6 indeed triggers the 3-fill, just before the collapse dries up. Now we can look back up through the collapse to make sure no effects can be dragged out to the right to resume it.

The trace makes other comparisons possible. For example, Master 40 gave up a huge bypass, but escaped collapse, holding on until, in late line marking, it gives up a hidden triple.

Sadly, too many expert writers bury these basic dramas, dismissing basic work as “singles”.

Next week, it’s PencilPress bottom right, page 41 at left and Master Class 50 on the right.