## Don't Understand Notation

Everything about Sudoku that doesn't fit in one of the other sections

### Don't Understand Notation

Okay, it's time to rake muck!

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`Why do we use notation like: [r5c1]=1=[r5c89]-1-[r6c9]when this makes more sense : [r5c1]-1=[r5c89]=1-[r6c9]`

By looking on either side of a cell, you know its relationship to a particular candidate in that cell.
daj95376
2014 Supporter

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### Re: Don't Understand Notation

daj95376 wrote:Okay, it's time to rake muck!

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`Why do we use notation like: [r5c1]=1=[r5c89]-1-[r6c9]when this makes more sense : [r5c1]-1=[r5c89]=1-[r6c9]`

By looking on either side of a cell, you know its relationship to a particular candidate in that cell.

Because there are two possibilities, either r5c89=1 or r5c89<>1. The first applies when the expression is read left-to-right r5c89=1, the second right-to-left.
ronk
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And why would I want to read it from right-to-left?
daj95376
2014 Supporter

Posts: 2624
Joined: 15 May 2006

daj95376 wrote:And why would I want to read it from right-to-left?

Because that notation is nice loop notation ... which is bi-directional, by definition. But you don't need to read it right-to-left, I suppose.

Why do we use notation like: [r5c1]=1=[r5c89]-1-[r6c9]

You can look at [r5c1]=1=[r5c89] as

exactly one of r5c1=1 and r5c89=1 must be true (strong link)

and [r5c89]-1-[r6c9] as

at most one of r5c89=1 and r6c9=1 can be true (weak link)
ronk
2012 Supporter

Posts: 4764
Joined: 02 November 2005
Location: Southeastern USA