ConstructionProblem4/ Solution

Terminology of notation: the 4x4 board has 4 partial boards A, B, C, D which are arranged clockwise, starting in north-west like this:

AB

DC

[1]  

Tderz: I give the 4 different orientation of the partial boards:

For easier copying the board is: (in editing mode it looks ok) ^[9]

X O . X

[2] +90°  

. X X O

[3] +180° (= mirrored ^[1])  

X . O X

[4] +270° (= mirrored ^[2])  

O X X .

Tderz

Solution 1: 3-4-1-2  

[edit]

Solution 1:

could be annotated like this

3-4
2-1

Solution 2: 1-2-3-4  

[edit]

Solution 2:

turning all +90° => forbidden position, but +180° creates
which has m-symmetry because all symmetrically arranged subboards have too: notation must be (and is):
1-2
4-3

[9]: copying for editing seems to make no sense here

ferdi: I certainly don't know what this is all about, but it helped you to find the solution ;-)

Tderz: Ferdi, I only wrote down the notation , because I thought that there would be many solutions, and wanted to streamline and classify the flux of incoming duplicates. Now I think that there won't be more than those with a 4-block in the center, because of the legality problem.

Thanks for the problem!

Tderz: Speaking of a 4-block in the center ...

Nascent solution 3?: 2-3-1-4  

[edit]

Nascent solution 3 exists only temporarily :-):

2-3
1-4

Shortly after adding the 4th partial board, the 4 stones must be captured.

... a fraction later ...  

therewith (illegal) solution 3 is different to other "solution " implying suicide.