I have some confusion on the definition of Single-Peaked function. Can anybody tell me the official definition of it?
It is intuitive to understand "Single-Peaked". However, what if the function has a flat part with its level lower than the peak? Can we say this function still Single-Peaked?
In other words, do we require the strict monotonicity on both sides of the peak for it to be "Single-Peaked"?
Thanks in advance.