The New Sudoku Players' Forum

by **CathyW** » Fri Dec 02, 2005 10:23 am

Finally cracked Killer no 3 from ND last night

Nice one - actually had to use a bit more maths to solve it!

Now for no. 4 ...

by **afjt** » Fri Dec 02, 2005 1:06 pm

CathyW wrote:Now for no. 4 ...

This one comes in the same category as the infamous djape 27th September one.

by nd » Fri Dec 02, 2005 1:36 pm

Yeah, it's a hard one..... but, I swear, it's solvable without trial & error! I created it using logic & then solved it to make sure. That said, the techniques I used to solve it don't fall within the "normal" techniques listed on my tips page (& which are programmed into the extant computer solvers). There are some additional starting tips in the comments on the Killer Sudoku #4 page, in response to DJApe's comment; tell me if that's not enough & I can help out.

by **afjt** » Fri Dec 02, 2005 5:06 pm

I had a stab at it last night, and although I had worked out all the tips myself, I didn't manage to finish it. That was a combination of the fact I wanted to get some sleep, and also because the grid was so covered in pen marks it was becoming unreadable. I may have another go tonight, but I suspect that I may end up using proof by contradiction !

by **udosuk** » Sat Dec 03, 2005 11:04 am

I solved ND's 4th puzzle with colouring, and left a couple comments in that blog page... I doubt it is really solvable using "pure logic", and perhaps when ND worked on nonet-8 the elimination steps were so complicated and intense that he applied minor T&E unaware (I'm fully prepared to be wrong here...)

Great puzzle though, keep up the great work!

For those stuck REALLY DESPERATELY, this pic might help them a bit (spoiler though, make sure you try your best first!):

http://tinypic.com/i4fuyv.png

by nd » Sat Dec 03, 2005 5:04 pm

Aha! I knew you'd be able to crack it.... Thanks for the image with the coloring. I think I need to solve the puzzle a 3rd time now to doublecheck everything again!

I've put your & afjt's comments on my blog now (sorry to put it in the holding tank but I have it currently set so that if you haven't got a previously approved comment it needs to be OK'ed by me--I resorted to this to avoid spam).

by **CathyW** » Thu Dec 08, 2005 5:54 pm

It's no good - still stuck on this one -

Will have to go and look at the hints from other solvers on ND's blog.

by **CathyW** » Fri Dec 09, 2005 10:14 am

Finally solved ND's 4th, thanks to tips in messages on his site.

by nd » Sat Dec 24, 2005 7:42 am

THought I'd bump the thread to point out that I've constructed a couple new ones, #5 and the latest, #6--

http://www.ndorward.com/blog/?p=75
http://www.ndorward.com/blog/?p=79

Both of them reasonably hard.

The New Sudoku Players' Forum

A couple killers I put together