unsolveable?

Can anyone solve this unicursal puzzle? Draw a box with an X inside and a half circle on the outside of each of the 4 sides. Start any where but you cannot retrace a line or lift the pencil.

Randy or Dawn McMannama writes:

First, this sort of puzzle can often by solved by a trick such as folding the page so the pencil draws two lines at once. I will assume in the rest of this posting that this sort of thing is not meant to be allowed.

Then, as is well known, there is no way to construct such a path if the desired diagram includes more than two 'odd vertices'

* Randy & Dawn McMannama Spoiler:

No, if I understand you correctly, it cannot be done. Each corner of the box is a meeting place for five lines. Therefore the pencil must either start in such a corner or end there. However, there are four

Mark Brader schrieb:

ObPuzzle: What two nits could I pick here?

Anyway, another way to do it is to draw the 'X' as a 4-pointed star, much like the Xbox logo ( http://images.google.com/images?q=xbox+logo ):

2 very weak ones:

ABXDE cannot be the X, as it contains X, and thus must be equal to a proper subset of itself and thus infinite.

You can start anywhere, not just at any of the six letters.

1 valid one:

AC is not the semicircle, AD is.

Phil Carmody schrieb:

Aargh! It always gets back at you, doesn't it? Picking nits, I mean?

Here I am, mentioning 2 nits, and there are actually 4: your three (of which only the 'start anywhere' I thought of), and the nit that since 'X' is a letter denoting a vertex, there are 7 letters in all.

Anyway, I hope it's clear to everyone I am only doing it for the fun of it - Mark posted a solution I'd never have thought of, and the nits do in no way detract from that.

Cheers