rjamil wrote:First of all, regret for replying late as I am still confusing in identifying guardian candidates for June 25, 2020 puzzle, as per
Cenoman's
OTP solution. I see 9 @ r1c7 as guardian candidate too
Well, it's not. 9r1c7 is a guardian for Steve's BUG-Lite+3 (later identified as such), but not for the full BUG+3 Cenoman used. Its guardians are (8r1c7, 9r1c9, 9r2c7) and there's no ambiguity about that at all.
, that's simply eliminate 9 from r3c9, being that if all guardian cells have same guardian candidate then eliminate that guardian candidate from (cells that sees) common peers of all guardian cells.
Once again, that's ambiguous terminology. Three different cells can't have the same
candidate (guardian or not). They can have the same
digit. Candidates are instances of a digit that are bound to specific cells, so they can't be shared by different cells. Thus, three different terms for three different concepts: guardian cell, guardian digit, guardian candidate.
In Cenoman's BUG+3 there are three
guardian cells (r1c7, r1c9, r2c7), two
guardian digits (8 and 9), and three
guardian candidates (8r1c7, 9r1c9, 9r2c7). Plain
guardian is a synonym for a
guardian candidate (not for a guardian digit or a guardian cell).
Secondly, a W-Wing and an XYZ-Wing moves are available, that's unable to solve the puzzle state, but, need not to be considered as BUG+n move at all.
Irrelevant. Any BUG situation can be solved with other techniques, but we're talking about BUGs now, so let's stick to that. The point of using a BUG instead of those other techniques is that it's often easier and more fun for a manual solver. It certainly doesn't mean that it's the only option.
I let Cenoman help with his own tutorial. I wrote mine
here. Read that again, and it should also explain how those guardian candidates are identified. That process leaves no doubt that 8r1c7 is a guardian. Since that cell has only three candidates to begin with, it can only hold one guardian, which means 9r1c7 can't be a guardian. The other reason is that there are four 9s in box 3 and two of them (9r1c9, 9r2c7) were already identified as guardians, so the other two 9s in that box must be non-guardians.
And lastly,
Cenoman's
faulty BUG+Lite claim confuses me a lot. So, thinking again the same puzzle state with same guardian candidate for all three guardian cells solves like
RW's simple logic.
Don't worry about the BUG-Lite logic for now. Try to understand the full BUG first. It's simpler because it deals with the full grid.
