cover up the bottom of this post if you want to slove this

try to solve this ,here are the rules you must connect all the numbers.
you may draw a total of 4 lines.lines must be straight,and you maynot retrace or go back on a line.you may cross lines.

...1....2....3

...4....5....6

...7....8....9

the solution...think outside the box.add points A and B

You start at the very top of the number 1, go through the middle of the 2 and clip the base of the 3 and head off in the direction of A (A probably needs to be further to the right, but it gives you the general idea). This first line slopes down to the right.
Next you slope down to the left going through the top of the 6, middle of 5 and base of 4 towards B. Finally hit the top of 7, middle of 8 and base of 9.

Originally posted by aspviper666 ...think outside the box Like it!

Originally posted by aspviper666 From the original post i.e. rules
lines must be straight

The lines in my solution are straight ... just not horizontal.

The first straight line goes diagonally downwards to the right at a very shallow gradient. The second goes downwards to the left at a very shallow gradient and the final one to the right.

This wouldn't work if there were points involved, but does because the numbers have 'height'.

Sorry I didn't explain this clearly the first time.

Originally posted by Diapason The lines in my solution [b]are straight ... just not horizontal.
This wouldn't work if there were points involved, but does because the numbers have 'height'.[b]

Absolutely right.

The problem posed indicated no points, mathematical or otherwise. The problem indicated numbers and those ar not pointlike.

Originally posted by Diapason The lines in my solution [b]are straight ... just not horizontal.

The first straight line goes diagonally downwards to the right at a very shallow gradient. The second goes downwards to the left at a very shallow gradient and the final one to the right.

This wouldn't work if there were points involved, but does because the numbers have 'height'.

Sorry I didn't explain this clearly the first time.[/b]

the numbers are supposed to be points or dots
(see thread title)
I used numbers so i could devise a notation system
to post solutions.
I can see where you got the idea about the height off the numbers.
I am sorry about any confusion.
cheers

This is a very interesting problem if you go beyond the famous original problem.

For example: If you put the points on a non-flat surface, for example a sphere or a torus, is the problem solvable with fewer than four lines? Perhaps only one line, circling?

Or: if you extend the problem, not only 3 by 3 but 4 by 4, how many lines are needed?

Or, further: If you, instead of using a 3 by 3 plane, use a 3 by 3 by 3 cube, how many lines are then needed to connect the dots? Or perhaps planes?

Originally posted by FabianFnas This is a very interesting problem if you go beyond the famous original problem.

For example: If you put the points on a non-flat surface, for example a sphere or a torus, is the problem solvable with fewer than four lines? Perhaps only one line, circling?

Or: if you extend the problem, not only 3 by 3 but 4 by 4, how many lines are needed?

Or, f ...[text shortened]... , use a 3 by 3 by 3 cube, how many lines are then needed to connect the dots? Or perhaps planes?

Yes a friend of mine proposed a solution involving a line encirling the world.I guess thats a way to solve it and definitely out side the box.
Good points and thoughts by all.
I am not a math dude myself.
thanks