This post details the basics and the easy solution of the fourth puzzle of the Lucky Panda Sudoku review, “insanely difficult” 192. It’s not with a bv map.
The bypass starts with a 3-fill and immediately resolves two. Then slink marking is confined to the middle boxes.
Columns dominate in line marking, which is aided by two hidden singles.
Did you spot anything on the line marked grid?
Going directly to the bv map, two XY railway segments lead to removals.
Which diagram would you prefer for constructing XY chains: the universal keypad grid, the Sysudoku line marked grid, or the bv map? Be honest, now.
Of course you do have to reference the full grid for the candidate victims. The longer ANL eliminates 8r9c9, creating another bv. The decisive blow is a reverse boxline, with the 2r8c6 removal activating box slink S2m to trigger a collapse.
Next week it’s all about LuckyPanda 240