page 406: + and - signs switched in a sentence?

[AI-medicine]

Hi,

I am sorry if I should be wrong and waste a little time of you, but I think there is a little error on page 406 in the book:

There's a sentence that says: "it will return a1+a2+a3-a7-a8-a9." after a kernel got applied on the following matrix: a1 a2 a3 a3 a5 a6 a7 a8 a9.

But the kernel that was used before on page 404 was: top_edge = tensor([[-1,-1,-1], [ 0, 0, 0], [ 1, 1, 1]]).float()

So shouldn't it be instead on page 406: "It will return -a1 -a2 -a3 +a7+a8+a9?"

A little below it also says on page 406: "So this filter detects horizontal edges—more precisely, edges where we go from bright parts of the image at the top to darker parts at the bottom." - which I would think fits to the kernel used at page 404, as such detected corners would end in a positive value after the kernel got applied.

Kind regards!