Let's have an invertible function $f$. Let's consider the intersection of this function and its inverse. The following hold:
1) If $f$ is strictly increasing, then the intersection points lie on the $y=x$, which means that one could write: $f(x)=f^{-1}(x)\Leftrightarrow f(x)=x$
2) If $f$ is strictly decreasing and odd, then the intersection points lie on the $y=-x$, which means that one could write: $f(x)=f^{-1}(x)\Leftrightarrow f(x)=-x$
3) If $g(x)=x+f(x)$ is one-to-one, then the intersection points lie on the $y=x$, which means that one could write: $f(x)=f^{-1}(x)\Leftrightarrow f(x)=x$
Is there any online resource (not books, but articles, free e-books, etc.) where each of those is mentioned? I haven't been able to find any resource that contains all of the above mathematical results.