In the following text, I wonder if it's grammatical to finish the sentence with also. it does sound weird to me. The sentence sound incomplete somehow and makes the audience wait for more.
Here this equation must be understood to mean not only that both sides have the same value when they are defined, but also that when either side of the equation is undefined, the other is also.
I know it's the other is also [undefined], but I've never seen a construction like that. If it's grammatical, what is it called?