If a set has NO lower bound then we say that the "GLB" is .
I am not sure if my solution for the following problem is correct, in my class I have never seen GLB to be −∞ . Could it not exist?
Evaluate LUB, GLB, maximum and minimum (if they exist) of {−n:n∈N}.
My answers:
LUB: −1
GLB: −∞
max: −1
min: none