Ratha (papertygre) wrote,

Sudoku, Invisalign, Microfinance

I took Damien to the airport this morning so that he could attend the ACM conference at UIUC. I'm realizing just how much time I spend with him as I think about the fact that he'll be gone until 2 AM on Tuesday.

Last night, instead of letting him pack, I showed him a spreadsheet I made to assist in solving sudokus. It shows the possible values for each unsolved cell based on straightforward elimination (horizontal, vertical, within quadrants) and has a supplementary sheet that points out when a value is the last one of its kind in its row, column, or quadrant. This essentially removes the "oh, duh" errors from the solving and helps reduce short term memory load. So the interesting puzzles are the ones where these sheets give you no new information and you have to apply cleverness to move forward. Damien had been working on a sudoku on my tablet (in Microsoft Sudoku) at the "Difficult" level and had reached an impasse, so for fun I plugged the current state of the puzzle into my spreadsheet. This revealed a few more numbers that could be filled in, but after that the puzzle seemed to be in a stuck state. There were about a dozen cycles (groups of 2, 3, or 4 cells which, between them, contain a known group of numbers) but no obvious way to solve any of them. We sat and stared at the puzzle for at least a half an hour, and I was somewhat vidicated to demonstrate that my spreadsheet, which I'd mentioned before, didn't actually necessarily remove the challenge from the game. Finally, he came up with a really clever solution -- he posited that a certain cell with multiple possible values in it contained a particular value, and collapsed other surrounding value superpositions based on that choice. Then he supposed that the cell didn't contain that value, and traced out the implications again. Doing this, he saw that a certain other cell ended up with the same value in it no matter what the initial choice was. Therefore this latter cell must contain that value, and after this, solving the rest of the puzzle was straightforward. I was impressed, not only at the approach but at the execution.


This week I signed up for Invisalign to fix the post-braces drifting in my lower (and, increasingly, upper) teeth. I'm seeing Dr. Roos in Redmond/Bellevue, who seems great. The parameters of my treatment are $3500 (after $1500 insurance contribution) and 11 months (1 month for shipment of first trays, 10 months of wearing trays), ending with a retaining nightguard and either a permanent bonded lower retainer or a second nightguard.

GAIM 2.0beta4 seems to have fixed the problems I was having with beta3 logging in to AIM and MSN over the last few weeks. I thought I was being childish to cross my fingers until the problem went away, but in the end I guess it did.

I was introduced to the idea of "microfinance" recently via a video by a company called Unitus that is somehow involved in enabling these types of transactions. I love this idea because it's not so much charity, as something that helps poor people help themselves. I made my Microsoft Giving Campaign contribution this year to Microfinance Opportunities' Financial Education for the Poor project.

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