The New Sudoku Players' Forum

[cathythorne]

I'm stuck and have been since I clipped the puzzle from the Saturday's Toronto Star 2 weeks ago. I would really appreciate help.

This is as far as I've gotten:

6 0 0 | 9 5 3 | 0 1 0
0 3 0 | 2 1 6 | 9 5 0
9 5 1 | 0 0 0 | 2 6 3
________________
0 9 0 | 3 0 0 | 1 0 0
3 0 8 | 1 0 9 | 5 0 0
1 0 6 | 0 0 5 | 3 2 9
________________
2 1 0 | 6 0 0 | 4 9 5
0 6 0 | 5 0 2 | 0 3 1
0 0 0 | 0 0 1 | 6 0 2

[ArkieTech]

There is a triple in row 9

Code: Select all

 *--------------------------------------------------------------------*
 | 6      2478   247    | 9      5      3      | 78     1      478    |
 | 478    3      47     | 2      1      6      | 9      5      478    |
 | 9      5      1      | 478    478    478    | 2      6      3      |
 |----------------------+----------------------+----------------------|
 | 457    9      2457   | 3      24678  478    | 1      478    4678   |
 | 3      247    8      | 1      2467   9      | 5      47     467    |
 | 1      47     6      | 478    478    5      | 3      2      9      |
 |----------------------+----------------------+----------------------|
 | 2      1      37     | 6      378    78     | 4      9      5      |
 | 478    6      479    | 5      4789   2      | 78     3      1      |
 | 4578   478    34579  | 478    34789  1      | 6      78     2      |
 *--------------------------------------------------------------------*


dan

[cathythorne]

I wish I was smart enough to just know that a triple can't do anything but take up 3 cells. As it is I had to look up what a triple meant. I'm stuck again, and I'll bet there's a simple explanation again. Could you recommend a simple-to-read site where I could learn some more techniques?

Thank you so much,

Cathy

[wintder]

I like scanraid.

http://www.scanraid.com/Strategy_Families

[ArkieTech]

Cathy,

In row 9 the columns 2, 4, and 8 must contain the numbers 4, 7, and 8.
Therefore column 1 cannot contain a 4, 7, or 8 so it must be a 5.

Hope this helps.

dan

[cathythorne]

Thanks Dan. Your first comment helped after I looked up "triple". I'm off to get educated at scanraid.

Thanks again and all the best.

Cathy

[Pat]

I'm stuck and have been since I clipped the puzzle from Saturday's Toronto Star 2 weeks ago.

This is as far as I've gotten:

Code: Select all

 6 . . | 9 5 3 | . 1 .
 . 3 . | 2 1 6 | 9 5 .
 9 5 1 | . . . | 2 6 3
-------+-------+------
 . 9 . | 3 . . | 1 . .
 3 . 8 | 1 . 9 | 5 . .
 1 . 6 | . . 5 | 3 2 9
-------+-------+------
 2 1 . | 6 . . | 4 9 5
 . 6 . | 5 . 2 | . 3 1
 . . . | . . 1 | 6 . 2



hi cathythorne,

in row 9,
there's a duo --

the {3,9} have only 2 cells available

-- reserve those cells for those digits

this solves the 5 for that row

[Cec]

"....in row 9,
there's a duo --

the {3,9} have only 2 cells available

-- reserve those cells for those digits

this solves the 5 for that row

Nice observation Pat to spot a "hidden pair" [39] in row 9. Personally I find it easier to spot "naked subsets" such as the naked quad [4578] in row 9 compared to spotting a hidden pair. The naked quad [4578] means any of these four candidates appearing in other cells in row 9 can be eliminated which then leaves a naked pair [39] in cells r9c3 and r9c5 which of course was the "hidden pair" spotted by Pat. I realize it's the same result and it's a personal preference in what one finds easier to spot. Thought I'd throw this in for interest.

Cec

[ronk]

Personally I find it easier to spot "naked subsets" such as the naked quad [4578] in row 9 compared to spotting a hidden pair.

Wouldn't that depend upon whether or not one is using pencilmarks

[Pat]

Personally I find it easier to spot "naked subsets" such as the naked quad [4578] in row 9 compared to spotting a hidden pair.

hey Cec,

before the "naked" quartet = {4,5,7,8}
i hope you see the "naked" trio = {4,7,8}
( as ArkieTech had pointed out )

[Pat]

I tend to look for naked stuff before hidden stuff.

one type is more obvious (evident, nude)
the other type is more obscure (hidden, clothed)

the only trouble is, what most of you consider evident, to me is hidden - and vice versa!

Precisely. The Emperor Has No Clothes!

i wish i'd asked at the time,
what exactly does emm mean---

[Cec]

Wouldn't that depend upon whether or not one is using pencilmarks

Excluding those having a gifted memory, I can't see how naked or hidden subsets (ie. pairs, triples or quads) could be identified or deducted without using a pencilmark grid.

hey Cec,

before the "naked" quartet = {4,5,7,8}
i hope you see the "naked" trio = {4,7,8}
( as ArkieTech had pointed out )

Yes Pat, I realized there was a naked triple [478] as pointed out by ArkieTech. I merely wished to show that identifying the naked quad [4578] and eliminating these four candidates where appearing in other cells in row9 leads to a naked pair [39] rather than trying to spot the hidden pair [39].

The naked pair [39] does not immediately result from identifying the naked triple [478] and then eliminating these three candidates where appearing in other cells in this row9. As I previously mentioned, my above post was intended to show Cathy that the same result can be achieved by spotting the naked quad [4578] as an alternative to spotting the hidden pair [39]

Cec

[Pat]

Personally I find it easier to spot "naked subsets"
such as the naked quad [4578] in row 9
compared to spotting a hidden pair.

Wouldn't that depend upon whether or not one is using pencilmarks?

Excluding those having a gifted memory,
I can't see how naked or hidden subsets could be identified without using a pencilmark grid.

well, Cec, that's where we differ -- the "hidden" subsets ( at least duos ) seem quite obvious to me without "pencilmarks" -- they become very hidden when you do add "pencilmarks"

[Cec]

Personally I find it easier to spot "naked subsets"
such as the naked quad [4578] in row 9
compared to spotting a hidden pair.

Wouldn't that depend upon whether or not one is using pencilmarks?

Excluding those having a gifted memory,
I can't see how naked or hidden subsets could be identified without using a pencilmark grid.

well, Cec, that's where we differ -- the "hidden" subsets ( at least duos ) seem quite obvious to me without "pencilmarks" -- they become very hidden when you do add "pencilmarks"

You are correct Pat and I applaud you for spotting the "hidden" pair without referring to pencilmarks. I can now see this is the point ronk was making in his above post.

In making my above comment on needing a gifted memory to spot naked or hidden subsets I was thinking more of the far greater difficulty of spotting triples or quads without the benefits of a pencilmark grid. I again reiterate the purpose of my initial post was to explain how some members, including myself, have stated their preference to identify a naked quad rather than a hidden pair when studying a pencilmark grid. As I said before, not everybody sees this alternative as being better than spotting a hidden subset so it is a personal choice and I merely mentioned this as an alternative for Cathy to consider.

"...i wish i'd asked at the time,
what exactly does emm mean---"

"emm" was a popular contributor to this forum and very helpful to new members. "emm" hasn't posted to the forum for quite some time now. She had a wonderful sense of humour and a gifted vocabulary. "emm" could mean anything - my grand-daughter's name is emily and she is known as "emm" - just a thought!

Cec

[udosuk]

Cec, I guess Pat was wondering what did emm mean with her "The Emperor Has No Clothes" remark.

I'm also puzzled.