# Math Challenge - July 2019

• Challenge
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Hey, I was lazy: "<" is on the keyboard ##"\leq"## is not. These details are trivial and left to the reader ;-)
That reminds me of a statistics course lecture. The lector said something like "..and since ##f## is injective, it is invertible..". Similarly, in algebra, saying something is a subgroup of ##G## is to be read as "is an isomorphic copy of a subgroup of ##G##".

Mentor
That reminds me of a statistics course lecture. The lector said something like "..and since ##f## is injective, it is invertible..". Similarly, in algebra, saying something is a subgroup of ##G## is to be read as "is an isomorphic copy of a subgroup of ##G##".
or omitting "almost everywhere" in measure theory.

I have also seen isomorphic for monomorphic (here, not in books), which I really dislike.