Theorem T000445
Compact ∧ Connected ∧ LOTS ∧ ¬Empty ⇒ Fixed point property
Let be continuous. For , if , then let be disjoint open neighborhoods with , , and for each , . Then for , , so is open, as is .
If has no fixed point, then , and since is Connected, or must be empty. But if , then has no maximum element, and likewise if , it has no minimum element.
This contradicts that if is LOTS and Compact and not Empty, then it has a maximum and minimum element, by the remark in Math StackExchange 4786659.
The converse ( Fixed point property ⇒ Compact ∧ Connected ∧ LOTS ∧ ¬Empty ) cannot be proven from other theorems or disproven from a counterexample.
You can learn how to contribute a theorem or counterexample here.