Sudoku Puzzles

Ferris wheel on the Thymes. 6:04

Oops, make that the Thames, not Thymes.

6:55 Maen

The London Eye

very easy today
proof of 9/21/06 tough:

1) Start with 22, UP 27
2) NakedTriple: (c3, c2, c1)=468 => ~c754=48, ~(b3, a2)=4
3) UP 34
4) Naked Pair: b31=12 => ~b8765=2
5) XWing: (bg8, bg6)=3 => ~(g97, b75)=3
6) h9=2 == i8=2 -- NP: ae8=24 == e8=1 -- d7=1 == HP: e87=12
=> ~ef9=2
7) UP 81

6.04 & 6.55 - How many guesses ??

13:27 but again, I bailed out with two guesses. Have a great day/night, all.

Dear Pat, could you please explain to me and other newcomers the meaning of '22 UP 27' in your solution -Step 1?
Ciao and thanks!
Vincenzo

a notational convention of unclear origin.
UP = unique placement, meaning naked single in a cell, box, column or row.
Start 22 simply means 22 cells given at start.

Easy techniques to 34.
Xwing 3s @ bg68, elim b57=3,g79=3.
a8=2==a8=4--e8=4==e7=4--e7=1==g7=1--g7=8==a7=8 forbids a7=2
Locked 2s @df7 elim. ef9=2. UP81

Someday or maybe in another life I'll see some of these places in person. Until then, I'm a happy viewer.

8:36 Easiest 'tough' ever.

Wow! That is quite the Ferris Wheel.

What a view this wheel allows!!!

Shiver me timbers, it's pirate day again... and aye, aye it's the London aye!

P.S. - Good afternoon to all!

Took me a while, but no guesses. Seemed easier than most 'tough' puzzles.

My proof for today's puzzle, is essentially the same as Kaz's:
Possible proof of tough sudoku of 09 21 06:
1) Start at 22 filled - the given puzzle. Unique Possibilities to 27 filled. (UP 27).
2) Hidden pair 12 at b13 forbids b1=6, b3=47, b789=2,b56=1 UP 33
3a) a8=2 == a8=4 -- e8=4 == More...

We've seen this picture before here - I remember seeing the cat waving from the top of the ride! An easy tough today.

OK so today’s puzzle is as tough as a junket sandwich, but it does illustrate the different approach I take to solving puzzles. On some puzzles it works well. If I followed conventional proof descriptions it would be 1) Start 22 UP 81

I don’t have the skills of people like Pat, Steve & More...

This is my first proof. Can someone please check it for me, especially the fc as I have just got to grips with them over the last few days.

Start 22
Up 26
locked 6s (h1,h2) remove from column UP 27
hidden pair 12 (b1,b3) remove from column and block UP 30
locked 8s More...

There he is again...second window in, fourth floor, center building. That cat is everywhere.

An easy tough!

This pic AGAIN? That's code for everyone submit more photos for the Tough!

Nice picture

08:24.

Wow I love sudoku!
Yew Love ya xx

Hi Bruce - really there is no difference between your approach and mine. Your idea, as you describe it - is nothing but a hidden triplet, which you reduce to a hidden pair, which is how I start my proof. It seems the difference is in presentation, not in the logic involved - unless I am mistaken.

BTW - the notational convention - UP - was developed at this site a few months ago as part of a long-winded discussion amongst a few regulars here( at that time - primarily DJ and Andrei). The problem was EF - easy fillings - that was used to mean both singletons in containers and easy techniques. More...

Hi Bruce
I understand your approach. It must be the Aussie way to solve these.

Thanks Steve, polite as always, even when correcting a greenhorn.

Nov. 23, 2007.

SE=7.2