The New Sudoku Players' Forum

[Steerpike58]

Hi there! I'm fairly new to Sudoku, and have learned all the basics (hidden pairs, pointing pairs, box/line reduction, etc) and several more advanced techniques such as x-wing, y-wing. I'd say I'm happy with my progress, but SLOW!

My initial technique at the moment (on paper) is to write down as small 'notes' in the box all the candidates for each square - something all the online tools do for you in a flash. But this takes time. Not only does it take time to do, but it ends up messing up the squares as you cross out 'found' items and becomes almost unreadable towards the end.

So one streamlining effort I've started is to do a 'first pass' looking for obvious naked singles, by looking at the board for 'well populated' existing numbers, and using those to quickly eliminate squares elsewhere on the board, and thus filling in those obvious candidates. I'm currently systematically going through all digits (1-9) and scanning the board for these eliminations. Only after completing this process do I then start noting candidates and following all the other techniques.

A slight variation on the above is to do the quick scan of the board, but not only fill in obvious 'singles', but also, note any obvious 'pairs' within a block. So, for example, when scanning for the number '1', I may find a block that doesn't have an obvious unique '1' location, but - clearly only has 2 possible '1's, and I'm noting those down during this first pass. My thinking is - it took time to do the first pass scan, so may as well capture what I find. Noting obvious 'pairs' within a block helps speed up early elimination because once you fill in a square (with something other than '1') that 'may have been' '1' but is not '1', then you can immediately determine the 'other' member of the pair in the block must be '1'. However, this has led to a few mistakes and I'm wondering if it's worth it.

So does anyone have any 'speed up' tips? I would note, my short-term memory is not great, so I can't rely on 'seeing' (remembering) things on the board too well!

[SteveG48]

In addition to looking for looking for naked singles, look for hidden singles.

[Yogi]

Hello!
I think most of us Sudoku solvers tend to move on to doing harder puzzles with devices which calculate the candidates, as we tire of writing and erasing them, but while you remain interested in doing some which are harder than those in newspapers and magazines, then here are a couple of ideas.

Never heard anyone else suggest this: instead of writing candidates in cells, which by definition means most of what you write will NOT be true, make simple notes alongside the puzzle of what you KNOW to be true about the location of given candidates, in terms of placement in rows or columns. A mark that may mean something like ‘I know that the 3 in this box lies in that row.’ Then you will not need to go on remembering that fact for the time being, but it may be helpful later.

Also, if you can find the 2019 post on Single Digit Eliminations, you may find the Box Analysis method (which I prefer to do pictorially) to be a useful method of identifying which candidates may be useful in short-chain patterns like Kites, Skyscrapers and Turbot-fish generally (and which are not.)

The earlier discussion about Pre-emptive Pairs, which turned out to be Naked Pairs to us, illustrates the recurring problem in the language of Sudoku. You will find that mostly in this forum we tend to use the Eureka terms described in Sudopedia Mirror. A simpler approach might be to watch the first few videos by Sudoku Swami in his Complete Course. He seems to use our terms. Interestingly, I’ve only just decided to watch his Pen & Pencil videos.
Thanx for prompting me to do that!