>>18
Sure, so let us ask the reCAPTCHA guys if there are enough unclassifiable numbers left on earth for a separate numeric captcha. After all, why keep good entertainment to myself?
the size of the input [sic] domain does not significantly impact the difficulty [...] What does [...] is glyph similarity
Like there is no relation. But no. If your only task was binary classification between e.g. '1' and 'l' you could probably do quite well at it.
At least I can actually follow a thread of discussion.
A thread of discussion, perhaps. I would not trust you with this particular one.