I think what he is saying is, if you remove preconceptions, e.g. that '+' means "addition" then you can infer that it means "multiply" and that the "+ 1" is imp

I think what he is saying is, if you remove preconceptions, e.g. that '+' means "addition" then you can infer that it means "multiply" and that the "+ 1" is implied, based on the answer. As a human, using our prior experience we will most commonly say that + means addition and will make that an axiom of our solution, which involves (for me at least) adding the result of the previous line to the sum of each line. 8 + 11 = 19 [ + 21 ] = 40 As a machine (or as a mathematician thinking with more flexible abstractions) the numbers are intractable, but the symbols are and perhaps it is more "logical" to look at each line separately and change the meaning of the symbols. 8 * (11 [ + 1 ]) = 96 The point is that humans have a different set of logical precepts to machines.