I think you may be missing the context of what the paper is presenting, here. It looks like the paper is solving relations between floating-point numbers—for ex

I think you may be missing the context of what the paper is presenting, here. It looks like the paper is solving relations between floating-point numbers—for example, “3.4 + x = 3.4; solve for x” is of the examples from the paper. Note that there are solutions other than x = 0.