Timeline for answer to Ten-T puzzle. Place nine sets of the ten given T-shapes in a 20x36 rectangle by RobPratt
Current License: CC BY-SA 4.0
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8 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| Mar 5, 2025 at 12:47 | comment | added | Weather Vane | @RobPratt it's taken me rather longer, but I finally solved it too. | |
| Feb 23, 2025 at 2:01 | comment | added | theonetruepath | For comparison, my 'slightly sharpened sledgehammer' approach which is simple backtracking with a beam search aided by scoring heuristic took 248.5 hours | |
| Feb 23, 2025 at 1:57 | vote | accept | theonetruepath | ||
| Feb 22, 2025 at 14:10 | comment | added | justhalf | ah, interesting. Thanks for sharing the details and some tricks, Rob. | |
| Feb 22, 2025 at 14:08 | comment | added | RobPratt | @justhalf Not sure how long it would have taken to solve directly. I got impatient and wanted to see some progress, so I changed from a feasibility problem to an optimization problem by adding a binary slack variable $s_{ij}$ to \eqref{1}, relaxing \eqref{2} from $=$ to $\le$, and minimizing the infeasibility $\sum s_{ij}$. This got down to objective value $4$ (one small T missing) but then stalled. To finish things off, I performed a local search by fixing the variables for two of the ten types at a time, and solving over the rest. Took a few hours (maybe longer than solving directly). | |
| Feb 22, 2025 at 5:49 | comment | added | justhalf | How long did the solver take for this one? | |
| Feb 22, 2025 at 2:43 | history | edited | RobPratt | CC BY-SA 4.0 |
added 5 characters in body
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| Feb 22, 2025 at 2:32 | history | answered | RobPratt | CC BY-SA 4.0 |