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# Sudoku/Reviews/Systematic Sudoku/Nakex83

This puzzle came from sysudoku.com.

## Solution with Simultaneous Bivalue Nishio

### First coloring

Some seed pairs with lower Gordonian cell number were examined and rejected. r5c5={36} looked better and some time was spent with it. A mutual resolution was found, but the coloring was then abandoned as not easily generating more results.
SBN on r5c5={36}

SBN coloring

• light orange cell: seed cell for chaining
• green: first chain. Convention: lowest digit or Gordonian cell number.
light green: alternate cell candidate within green chain.
• red: alternate chain.
light red: alternate cell candidate within red chain.
• purple: mutual elimination.
• light purple cell: contradiction (multiple in region or empty in color)
• light blue cell: mutual resolution (as only colored candidate in cell)

### Second coloring

The next seed pair was r2c3={34}. This found a contradiction in the 4 chain, hence r2c3=3, and consequences.

SBN on r2c3={34}

### Third coloring:

r5c2={75}. Contradiction found in the 5 pair, so r5c2=7. Easy to the end.

SBN on r5c2={75}