Re(3): Listener 4360: What a Turn-up! by IOA IP: 188.8.131.52 Posted on September 12, 2015 at 06:47:57 PM by Gerry Leversha
Sorry if I was unclear. The point I was making distiguished between the placement of the representation of 1 as a subset of a set of seven line segments and the appearance of the 1 itself in the cell. If the set of segments is placed centrally in the grid, the 1 appears to the right, and so the result of a half turn is to show a 1 on the left of the cell. This is not acceptable as a representation of 1. Hence, in order to achieve a half turn which maps 1 to 1, the representation must be placed to the left of the cell (so that 1 appears centrally). Now a half turn would then produce an inverted representation on the right of the approapriate cell. But the 1 still appears to be in the centre of the cell.
Hence I think that the 1s must appear centrally,anything else being wrong.
This whole procedure appears to me to so artificial that it inclines me to think that there should not be any 1s in the grid. But now the problem is insoluble. Replies: