dailysudoku.com

RobertRattley · Joined: 24 Jun 2007 Posts: 118 Location: Australia

An easy "very hard" in that it wasn't very time consuming for me.

Fascinating puzzle. It started to fall into place like an "easy". Basics went so far that it seemed to be swimming in possibilities.

I chose an x wing that created an xy wing, but that didn't get far. Then I spotted a twin xy wing, either of which would do, that led to another twin xy wing, but this time only one helped. By "twin" I mean two xy wings on the same 3 digits that share two cells.

A surprising 4 stepper, considering how far the basics went.

I'm up after midnight taking advantage of my time zone every now and then to post first, but I won't go all the way today. Instead, I look forward to seeing who can come up with fewer steps, perhaps even only 1.

hughwill · Joined: 05 Apr 2010 Posts: 424 Location: Birmingham UK

About time there was a VH. Not that it's Monday yet here, but I bet
it can be done with a

Marty R. · Posted: Mon Aug 18, 2014 3:45 am Post subject:

Same as Hugh but my pivot was in r8c5.

hughwill · Joined: 05 Apr 2010 Posts: 424 Location: Birmingham UK

After Basics:

arkietech · Posted: Mon Aug 18, 2014 11:42 am Post subject:

Clement · Posted: Mon Aug 18, 2014 12:35 pm Post subject: Aug 18 VH

dongrave · Joined: 06 Mar 2014 Posts: 568

After solving this one using standard VH moves, I went back and examined it for a long time and eventually found two other chains that solve it in one step but neither of them are as short (so consequently not as nice) as Arkietech's solution. One of them is similar to a recent JC Van Hay solution that he referred to as 'nice' in his response to one of Keith's posts and I'm wondering how it should look in Eureka notation. In 'non-Eureka' notation it could be described as follows: r9c4 = 2 or 8; if it's 2, then r8c5=3 -> r8c9<3> r2c9=3; if it's 8, then r9c8<8> r8c9=8 -> r2c9=3; therefore r2c9=3. How do write this out in Eureka notation? Do you just list the sub-expressions for each starting number separated by semicolons and then end it with '=> r2c9=3'? Thanks in advance, Don. Oh! By the way, you know what I noticed? It sure is a lot easier to find chains if you already know the solution!

rmireland · Joined: 21 Sep 2013 Posts: 33 Location: New Orleans

I agree with dongrave and have also noticed how easy it is to find chains when working backwards. I would also appreciate a link to a Eureka syntax source to know how to exactly translate my "either this or that" logic into Eureka.
Another point, if I may. If I don't already know the answer, and I am just working with a bi-value cell and tracing the consequences of the two possible values to find common eliminations or contradictions, how is that not "trial and error"?
And maybe it's asking a lot, but I would love for someone (like Clement, maybe) to translate this verbatem into plain English: (2=7)r8c3-(7=2)r2c3-(2=8)r1c2-8=2)r1c9; r8c9<>2
In an ideal world, if I have the chain above, shouldn't I be able to, from the chain alone, determine the final elimination without reference to the puzzle?
I know I ask a lot of questions. It's just my nature.
Thanks, Rick

Marty R. · Posted: Wed Aug 20, 2014 5:05 am Post subject:

dongrave · Joined: 06 Mar 2014 Posts: 568

Marty R. · Posted: Wed Aug 20, 2014 12:59 pm Post subject:

dongrave · Joined: 06 Mar 2014 Posts: 568

Hi Marty, It sounds like you took offense to my bashing of Eureka. (I didn't mean to hit a nerve.) I thought that the rest of my sentence explained what was wrong with it - and that is that it's not intuitive. The fact that people capable of solving the most advanced puzzles in the world (like Keith and Van Hay) are not using it speaks volumes. And the fact that people (like Rick and me) are begging for someone to explain it illustrates just how cryptic it is. The most confusing (and flat out 'wrong' in my mind) was the use of the '=' to denote something completely different than what the entire world knows it to mean. And then enclosing 2 numbers along with it in parentheses at the beginning of each component of an expression takes the word 'cryptic' to a whole new level. Conciseness is not everything. They really should have given some regard to making it more intuitive. Thanks, Don.

Marty R. · Posted: Wed Aug 20, 2014 3:32 pm Post subject:

rmireland · Joined: 21 Sep 2013 Posts: 33 Location: New Orleans

Hi Marty and Don,
Please don't go offline for this.
Before seeing the most recent post here, I have just posted to the AUG 20 VH in hopes of continuing this discussion there.
If you think this is not of general interest, then could we start a thread somewhere, please!
Rick

dongrave · Joined: 06 Mar 2014 Posts: 568

That sounds great to me Rick - but of course it's up to Marty! I'm glad I didn't offend him. I thought for a minute that maybe he was involved in the design - and here I was bashing it. Even though I despise it, that doesn't mean that I don't want to learn it! I'll check back in a little while and see what Marty says! Thanks, Don.

Marty R. · Posted: Wed Aug 20, 2014 7:13 pm Post subject:

I was hardly involved in the design; in fact I was years late in learning it.

If you have any questions or comments that are general and don't involve a specific puzzle, then post in the Solving techniques, and terminology sub-forum.