On Logical Space In Tractatus Logico-Philosophicus

How to comprehend logical space in Tractatus Logico-Philosophicus, it involves how to comprehend Logic, but there are many vague in tradition. Completeness is a standard of demarcation for logic in my thesis, we can demonstrate completeness of propositional logic by isomorphism, namely logic and modal (structure of world) have a same structure, then the completeness of first-order logic can be demonstrated, first-order logic and first-order modal of world are isomorphism, at last those theories which build on first-order logic such as the Piano Arithmetic, Set Theory, Type Theory of Russell are incomplete, namely they are not isomorphic to modal. So the logical space just be logical space of first-order logic, and we can defend the view that logic and world have same structure, since first-order logic is isomorphic to world.