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Vanhegan Extreme Random - Flatters to deceive...

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peterj

Joined: 26 Mar 2010
Posts: 974
Location: London, UK

Posted: Tue Dec 28, 2010 8:02 pm Post subject: Vanhegan Extreme Random - Flatters to deceive...

Code:

*-----------*
|...|713|...|
|..4|9..|3..|
|.1.|5.2|.8.|
|---+---+---|
|4.6|2.8|139|
|9..|...|..4|
|251|4.9|6.8|
|---+---+---|
|.6.|1.4|.9.|
|..9|..7|2..|
|...|895|...|
*-----------*

Feels like it's going to be easy - but with most of the grid filled it still needs work!

Marty R.

Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA

Posted: Tue Dec 28, 2010 10:54 pm Post subject:

Rather unusual for an Extreme to have 34 givens plus freebies too.

Quote:

In the potential Type 6 UR (15), r2c9=7 or r9c8=4. The former is invalid and the latter solves the puzzle

peterj

Joined: 26 Mar 2010
Posts: 974
Location: London, UK

Posted: Wed Dec 29, 2010 8:51 am Post subject:

I didn't see anything constructive from the UR, perhaps I didn't persevere long enough following the implications.

I found a simple ANP...

Code:

#1 ANP(15=7)r28c9 - (7=5)r2c1 - r79c1=r7c3 ; r7c9<>5
#2 xy-wing(13-6) r9c1 ; r3c9<>6

... and a one-stepper from targetting 5s...

Code:

*--------------------------------------------------------*
| 568 9 58 | 7 1 3 | 4 56 2 |
| (7)-5 2 4 | 9 8 6 | 3 15 b(1)5(7) |
| 367 1 37 | 5 4 2 | 9 8 67 |
|------------------+----------------+--------------------|
| 4 7 6 | 2 5 8 | 1 3 9 |
| 9 38 38 | 6 7 1 | 5 2 4 |
| 2 5 1 | 4 3 9 | 6 7 8 |
|------------------+----------------+--------------------|
| 357 6 357 | 1 2 4 | 8 9 b35 |
| a158 48 9 | 3 6 7 | 2 a145 &(1)5 |
| 13 34 2 | 8 9 5 | 7 146 136 |
*--------------------------------------------------------*
Almost Kite(5)
kite(5) ; (5)r2c9=r7c9 - r8c8=r8c1
||
(5)r8c9 - (1)r8c9=(1-7)r2c9=r2c1 ; r2c1<>5

daj95376

Joined: 23 Aug 2008
Posts: 3854

Posted: Wed Dec 29, 2010 11:05 am Post subject:

peterj wrote:

I didn't see anything constructive from the UR, ...

I'm not sure how Marty resolved the UR, but the following gets the job done.

Code:

+-----------------------+
| . . . | 7 1 3 | . . . |
| . . 4 | 9 . . | 3 . . |
| . 1 . | 5 . 2 | . 8 . |
|-------+-------+-------|
| 4 . 6 | 2 . 8 | 1 3 9 |
| 9 . . | . . . | . . 4 |
| 2 5 1 | 4 . 9 | 6 . 8 |
|-------+-------+-------|
| . 6 . | 1 . 4 | . 9 . |
| . . 9 | . . 7 | 2 . . |
| . . . | 8 9 5 | . . . |
+-----------------------+

solved = 59 bivalue = 13 polyvalue = 9 elims = 31

+-----------------------------------------------------+
| 568 9 58 | 7 1 3 | 4 56 2 |
| 57 2 4 | 9 8 6 | 3 15 157 |
| 367 1 37 | 5 4 2 | 9 8 67 |
|-----------------+-----------------+-----------------|
| 4 7 6 | 2 5 8 | 1 3 9 |
| 9 38 38 | 6 7 1 | 5 2 4 |
| 2 5 1 | 4 3 9 | 6 7 8 |
|-----------------+-----------------+-----------------|
| 357 6 357 | 1 2 4 | 8 9 35 |
| 158 48 9 | 3 6 7 | 2 145 15 |
| 13 34 2 | 8 9 5 | 7 146 136 |
+-----------------------------------------------------+
# 31 eliminations remain

r28c89 <15> UR[(4)r8c8 = (7)r2c9] - (7=6)r3c9 - r9c9 = (6-4)r9c8 = (4)r8c8

It's one of those rare occasions where I needed to write a discontinuous loop.

peterj

Joined: 26 Mar 2010
Posts: 974
Location: London, UK

Posted: Wed Dec 29, 2010 12:09 pm Post subject:

daj95376 wrote:

but the following gets the job done.

Nice. That'll do it!

Marty R.

Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA

Posted: Wed Dec 29, 2010 1:41 pm Post subject:

Quote:

I'm not sure how Marty resolved the UR, but the following gets the job done.

Danny, if you play the 7 in r2c9, it leads to an invalidity, leaving 4 in r8c8 as the only way to kill the DP. This time I'm confident, as I've done it three times.

tlanglet

Joined: 17 Oct 2007
Posts: 2468
Location: Northern California Foothills

Posted: Thu Dec 30, 2010 1:58 pm Post subject:

Another alternative is an almost xy-wing.

Code:

*--------------------------------------------------*
| 568 9 58 | 7 1 3 | 4 56 2 |
| 57 2 4 | 9 8 6 | 3 15 157 |
| 367 1 37 | 5 4 2 | 9 8 67 |
|----------------+----------------+----------------|
| 4 7 6 | 2 5 8 | 1 3 9 |
| 9 38 38 | 6 7 1 | 5 2 4 |
| 2 5 1 | 4 3 9 | 6 7 8 |
|----------------+----------------+----------------|
| 357 6 357 | 1 2 4 | 8 9 35 |
| 158 48 9 | 3 6 7 | 2 145 15 |
| 13 34 2 | 8 9 5 | 7 146 136 |
*--------------------------------------------------*

Flightless AXY-wing -367 vertex(67)r3c9, pincers (37)r3c3 & (36)r9c9 with fin (1)r9c9; r9c2<>3
(3=8)r5c2-(8=3)r5c3-[xy-wing (367)=(1)r9c9]-(1=3)r9c1; r9c2<>3

or if my chain is improperly formed,

If xy-wing is true plus transport: (3)r3c3-r5c3=(3)r5c2;
If fin is true: (1)r9c9-(1=3)r9c1;

Ted

daj95376

Joined: 23 Aug 2008
Posts: 3854

Posted: Thu Dec 30, 2010 6:43 pm Post subject:

Ted, an alternate perspective on your chain. BTW: nice find!

Code:

*--------------------------------------------------*
| 568 9 58 | 7 1 3 | 4 56 2 |
| 57 2 4 | 9 8 6 | 3 15 157 |
| 367 1 37c | 5 4 2 | 9 8 67d |
|----------------+----------------+----------------|
| 4 7 6 | 2 5 8 | 1 3 9 |
| 9 38a 38b | 6 7 1 | 5 2 4 |
| 2 5 1 | 4 3 9 | 6 7 8 |
|----------------+----------------+----------------|
| 357 6 357 | 1 2 4 | 8 9 35 |
| 158 48 9 | 3 6 7 | 2 145 15 |
| 13e 4-3 2 | 8 9 5 | 7 146 136e |
*--------------------------------------------------*

(3=8)r5c2 - (8=3)r5c3 - (3=7)r3c3 - (7=6)r3c9 - (6=13)r9c91 => r9c2<>3

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