A good starting point is the YouTube channel Cracking the Cryptic, linked below, which you may already be familiar with. He does superb sudokus which employ advanced techniques. This includes a LOT of variants.
Variants may be a turnoff if you’re not starting light. My favourite very light variant is this one:
Normal sudoku rules apply but in the final grid, every clue is wrogn (aka invalid)...
Clues are valid if: [Everything is "totally standard" Undar promises...]
-Digits in a killer cage sum up to the small clue in the top left of the cage;
-Clues outside the grid are correct X-sums. ie Clues show the sum of the first X digits in that direction where X is the 1st digit.
- Clues outside the grid are correct skyscraper clues. ie The digits in the grid represent the "heights" of skyscrapers. Clues represent the number of skyscrapers seen from that direction. Taller skyscrapers block shorter ones.
-Digits on a thermometer increase from the bulb end
-Digits separated by a black dot has a ratio of 1:2
-Digits separated by a white dot are consecutive
-Digits separated by X have a sum of 10
-Digits separated by V have a sum of 5
-All digits in a circle appear in the 4 cells touching it
-Maximum cells are larger than all 4 adjacent cells
That one is just crazy... but solvable. Apparently, there's a new one from just a week ago that is similar in construction - https://youtu.be/JTkvR5M0yFo (you'll note the 2h long video)
> Group Sums: A number in a small circle indicates the sum of the digits in the cells covered by the corresponding circle. These digits may or may not repeat. Arrow Sudoku: Digits along an arrow must sum to the number in the corresponding circle. In this Sudoku all group sum clues contain a comparison operator. The clue ≥26 for example indicates a sum of at least 26. An arrow between two cells points to the smaller number.
You'll note that I picked a particular channel with the longest videos.
The community around that channel has some particularly difficult puzzles especially if you're willing to go beyond "normal Sudoku rules apply."
Sudoku variants, and even more importantly human-designed puzzles, are where all the fun is.
I grew bored with classic machine-generated sudoku ages ago because it began to feel very mechanical. Adding variant rules like thermometers lets puzzle setters use more bits of logic that are satisfying to reason about.
Puzzle creators are still finding new theorems about how sudoku works, even within the standard rules, and creating puzzles that teach them to solvers. The Phistomephel Ring, an extension of set theory, applies to every single sudoku grid in existence.
As a middling solver, many recently-featured puzzles are too difficult for me, but it’s still fascinating to watch CTC solve them.
See, that might be cultural background or whatnot, I don't know, but some people find those cartoons to be a nice touch, and they admire the clarity of exposition of The TeXbook.
I'm the proud owner of the entire 6 vol Computers and Typesetting series (of which the former title is vol A), and have worked through sizable portions of those. I also read mot of the 680 pages of Knuth's Digital Typography monograph. I also owned one LaTeX book at some point. I admire the depth of Knuth's knowledge (typographic and otherwise), the sheer diligence, his quest for quality, all of that. Those lion doodles though, the author's urge to land another witty remark, come up with another finely crafted reference, and how he's prone to hint at stuff instead of writing a proper documentation are not aspects of his work that I enjoy.
I've wondered where this stuff ends up after donating to charity. Is there a set of less fortunate people that could really make use of these things? Are there people eager to add more of these items to their "collections?" Do the charities end up discarding large percentages of this stuff?
Technically, they didn't oppose it, but they didn't support it either, as members had mixed feelings about the approach, which I'll paraphrase as it partly being a disguised tax cut for the wealthy rather than a revenue neutral carbon fee.
I personally support offsetting carbon taxes against other taxes, but since it would be regressive, I'd lean towards mitigating that in whatever compensatory tax cuts were introduced.
That can work too, though it's still probably regressive, as some people have more resources to adapt than others.
And if the policy is regressive then you face the danger of it blowing up in your face. For example, see what happened when the rich in America seized most of the benefits of globalisation, now we have Presidents threatening to burn it all down and being popular in doing so. If you actually want carbon reduce toon to be successful you need to factor in the politics, both getting the wealthy and powerful on board and getting the average man in the street to feel that he's not being screwed (which some people will tell him he is, even if he isn't).
Maybe, but I would kind of assume that poorer people already end up emitting a lot less carbon since most carbon emitting activities already have a significant cost involved.
I'm not so sure: poorer people often have to drive further, in clunkier cars. In any event, it's likely more 'regressive' than income: a rich person might earn 10X, but generate 2X the carbon. I bet there's data for this, though.
Because of the refund, 2X the carbon doesn't mean 2X the taxes. Someone who emits 120% of the average amount of carbon pays twice as much as someone who emits 110% of the average, but emits less than 10% more.
I can recommend Mastering Regular Expressions by Jeffrey Friedl. He goes into great detail on regexp performance and the reason various expressions are slow.
I picked up an older revision from abebooks or ebay. The Python 2.7 online docs recommend revision 1 and states later revs don't cover Python.
