the argument about pinning down semantic markup vs leaving it as late as
possible can be viewed in the same framework as the arguments for late vs
early binding in programming languages.

I think in the case of a rich and ever growing field like mathematics
late-binding is pretty much essential --the later the better.

Mathematicians have developed the uncanny ability to carry along unbound terms
until it's absolutely essential to bind them, which is why when reading a book
on lebesgue integrals an expression of the form
$\int f+g =\int f + \int g$
makes perfect sense to a mathematician but no sense to mathematica.

Best Regards,

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