*nods* It would probably make more sense if you'd encountered the electronic version already, which I was expecting most interested readers of this LJ to have done by now. If I were to publish a book of these (which seems unlikely :-) I'd make sure to provide a clear explanation at the front, and some sample problems with solutions.

The aim is to fill in the grid with a network of lines connecting together all the blobs and using all of the squares. Each square is either a T-piece, an endpoint (blob), a corner or a straight-edge, as shown by the small symbol in the corner of the square. So in each square you have to draw a large version of the small symbol, but it can be in any orientation so you have to work out which way round each one has to go.

The one without a thick border is the harder version, in which each edge of the grid is considered to be connected to the opposite edge, so that some of the connections in the network can wrap round from one side to the other. The thick-bordered one is the easier one in which this doesn't happen.

Although I really like logic based puzzles, you have a tendency to refer to ones which I hadn't encountered previously - I've aquired a small Su Doku addiction after your last post ;) Probably me being a Windows user these days, I guess.

I'd not come across this puzzle before, but your explanation is clear and concise, and I will be printing these out to have a play. In fact, I've just found your puzzle games page... must resist downloading at work.... (Thanks!)

Argh, I forgot to mention two important points: the correct solution is a single connected network (you can reach any square from any other square by following lines), and is also acyclic (there are no loops, i.e. there is always only one way to get from any square to any other). Knowing those things allows you to make a lot of useful deductions, and the puzzle is probably not uniquely solvable without making use of at least one of them.

(In the electronic version, these are enforced by the solution checker so you have some chance of figuring them out for yourself...)

Ohhhkay, Net is good; can get the bordered ones done pretty quickly.

But, I haven't yet managed to get any of the wrapping ones solved. I've got a few to a point of being hopelessly tangled in knots, with several squares blatantly not connectable with the rest of the configuration, but I haven't found any obvious starting points (like straights/Ts on the edges in the bordered version, for example), apart from occassionally-occuring straights between two end points. This makes it seem a lot more like trial and error (or randomly twisting things round and restarting again several times from the beginning for ages until stumbling over the correct solution) than anything involving logic. Am I missing some key point, or is the wrapping version really that ... random?

I also meant to ask whether there's a size that's easier for the wrapping version, to get the hang of it?

... apart from the straights between two ends - and grouped ends where there's only one direction out for some of them, I should have said.

There are quite a few possible starting patterns you can look for in a wrapping grid. You're correct that a straight between two endpoints is one of them. Others include:

• an endpoint surrounded on three sides by other endpoints (the centre one only has one direction it can point)
• a corner piece surrounded on three sides by endpoints (the corner piece must have a connection on the remaining edge so as not to connect two endpoints into a dead end)
• a T-piece surrounded on three sides by endpoints (again, it must connect on the remaining edge otherwise it just connects the three endpoints together)
• two endpoints and two straights arranged in a 2x2 square with opposite pieces identical (considering both ways for one of the straights to point should convince you that the endpoints cannot possibly connect on either of the two sides that don't border one of the two straights).

Also, keep in mind that a corner piece is always connected on one side if and only if it is not connected on the opposite side; so if one of the above deductions allows you to deduce that some piece has a connection on a particular side, and the next piece in that direction is a corner, then you know the piece beyond the corner does not have a connection on the near side - which allows you to nail down its orientation completely if it's a T-piece.

There are others as well, mostly more complex forms of dead-end avoidance. Those are just the first few that sprang to mind. It's certainly not random guesswork - I wouldn't expect to ever meet a wrapping Net puzzle I couldn't find somewhere to start on.

Thank you! That clarifies several things I'd been doing instinctively in the bordered versions, that I hadn't extrapolated into conscious thought for the wrapping ones. I shall tackle them later. (Not now, not at work. Really not. Honest. I can resist. *cough*)

Now all I need is a "lock" option for tiles so I don't forget which ones were set that way for a reason darnit... ;)

Middle-click, or shift-click if you don't have a middle mouse button.

Woo! Excellent.

And I just solved one, too *beam*

Oddly, that has made more difference to solving the wrapping ones than anything else! Much obliged :)