Thursday, 26 September 2013

TVC XVI Practise

Hello from Vancouver. Currently travelling before the WPC in Beijing. Need to be relaxed when I arrive there. Although maybe adding a small jetlag isn't totally the smartest thing. I was better located in Australia for that.

I wasn't sure if I could post any puzzles this week for the upcoming TVC XVI at Logic Master India.. I wrote a few puzzles on the plane, so I figure I'd share those. I hope they are of some use to people. Hopefully I will be able to compete in the last few days of the CTC and the last TVC. We will see. Everyone have fun at least.

There are four Tapas in this post.
The first puzzle is a Symmetric Tapa. This rule is very influential in the solve, so you really don't need many clues if you place your rectangles smartly. This one has four clues, but really shouldn't be that difficult a solve. I made it 11x11 as that way the rectangles would less likely share an edge if I placed all dots on grid points.
The second puzzle is a Toroidal Tapa. I like this variant. It's a bit trickier to design as you need to set a lot more blocks to make sure you can guide the wall where you want it to. I think this is a genre that can always use some practise, especially with looking around the edges of the grid. This puzzle is 12x12 as I liked this pattern of givens.
The third puzzle is a Transparent Tapa. This is the only genre that hasn't previously appeared on a TVC, so I figured I should at least make one of these. Although people can find a few of them on Prasanna Seshadri's blog. Oddly enough this rule change only means there is one clue that is invalid in normal Tapa. This one is also 12x12. I made an opening and then I noticed it would work more effectively in the corner of the grid. But to make a nice pattern of givens it would be better for the grid to be 12x12.
The fourth puzzle is a Alternative Tapa. This is the hardest of the four puzzles. This is not caused by the variant, as it's not overly influential in the solve. But the normal Tapa bit is pretty challenging and should give you all a bit of a challenge. Although maybe with the CTC you've had enough of those already. This one is 11x11 as it worked nicely with the TVC XVI pattern of letters.

Enjoy and have fun this weekend.

Puzzle can be found below.

Rules for Tapa

3. Symmetric Tapa

Follow regular Tapa rules. Part of the wall should have rotational symmetry in the largest possible rectangle having a black dot in the centre.

5. Toroidal Tapa

Follow regular Tapa rules. Additionally the grid is wrapped around the four edges.

6. Transparent Tapa

Follow regular Tapa rules. In this puzzles the Tapa clue cells can also be coloured. The means that every clue cell is valid for 9 cells instead of the normal 8 cells.

10. Alternative Tapa

Follow regular Tapa rules. For each set of identical letters, exactly one is coloured. The rest remain white.


  1. Alternative tapa: One could use uiqueness logic in R7C1. I could not see a god logical way to get past that 122 clue.

  2. The symmetric Tapa was quite easy, just need to keep track of the rectangles, which was a bit difficult to do on paint and should be easier on paper.

    Toroidal was my favourite of this set, but it didn't do anything to lessen my worries that this will be horrible to keep track of in a competitive environment. Really nice use of connectivity though, especially the parts around the middle.

    Transparent was actually the hardest of these 4 for me. Not sure if I missed something obvious. I started around the bottom left. I feel I'm missing something with the 1-1-1,5 couple but I'm not seeing what. Anyway, nice puzzle, even if it was difficult to get through.

    In Alternative, I saw the interactions between the middle 4 clues helping the solve a lot, I got the entire left 3 columns easily, and then it was about using those interactions little by little to mainly limit the 6. Really well constructed.

  3. It took a while to get the Toroidal to work. I had a bunch of places where I knew connectivity would force uniqueness, except I kept creating loops. Then of course it can't be unique as either one of the connectivity points would not be necessary to create a valid wall.
    The Transparent Tapa works anticlockwise from the left bottom corner, which was the opening I mentioned in my post. The right bottom 6,4 and 22 is where it continues. I don't think there's much to be deduced from the 111/5 combo before you do that part.
    The middle 4 clues was what I put down first and designed the rest around them. I liked how they interact, although it's not really obvious to spot from the get go. When 4 clues are that close together, you know there will be interactions.

    1. Ah good then, I followed the right path with the Transparent Tapa. I dunno why I just always felt I was missing something. Maybe that comes from knowing a few "secondary"(ones that get caused due to a little influence from surrounding cells) patterns from the ones I've written.

  4. Transparent tapa: Some of it was hard.I got the rectangle R7-12C1-6 and the top-right 4x4 rectangle first,( you have used some nice clue combos there) then the middle part.