There are mathematical systems that do not use some of the laws, for non-accusative algebra, non-commutative algebra, non-commutative geometry etc.
About Closure as a must-have term in general, please read about "Warning Signs of a Possible Collapse of Contemporary mathematics"
http://www.math.princeton.edu/~nelson/papers/warn.pdf
by Edward Nelson (
http://en.wikipedia.org/wiki/Edward_Nelson ).
Here is some quote from his paper:
Edward Nelson and most (if not all) mathematicians, understand Closure as a fundamental property of deductive systems, where each deductive system is first of all a closed framework, that is closed by a set of axioms, where any mathematical activity is done under Closure.
Godel, by using the axiomatic method showed that any axiomatic framework that is strong enough to deal with arithmetic, cannot be consistent AND complete.
It means that in such strong axiomatic frameworks there are true statements expressible in these axiomatic frameworks that are un-provable by the axioms of these axiomatic frameworks.
If we wish to save the consistency of such strong frameworks, we have to accept incompleteness as a fundamental property of the mathematical science, because the most interesting mathematical systems are strong frameworks.
In other words, we seriously have to reconsider Closure as a must have principle of the mathematical science.
I choose Non-locality as a fundamental principle of strong axiomatic frameworks, such that there exist
y with respect to framework X, such that
y belongs (it is true under X) AND does not belong (it is un-provable under X) to X.
From this non-local view
y belongs XOR does not belong to X, is a contradiction, exactly as local
z belongs AND does not belong to X, is a contradiction.
Let
n=1 to ∞ and let
k=0 to
n-1, where
n or
k are atoms (they are existing AND empty things, exactly as {} is existing AND empty thing).
Definition1: Given
n it belongs NXOR does not belong to
k.
Definition 2: Given
k it belongs XOR does not belong to
n.
Since
n or
k are atoms, they are not elements of each other, such that they are independent under Membership.
Independent Membership enables the existence of atoms as building-blocks of some complex, where a complex is the result
n AND
k atoms (no complex is only
n or only
k).
Now back to the real-line, by this NXOR\XOR Logic (where A,Not-A are F,F or T,T in the case of Non-locality, or A,Not-A are F,T or T,F in the case of Locality
http://www.scribd.com/doc/16542245/OMPT pages 26-29), any
k-D is Local w.r.t any
n-D, and any
n-D is non-local w.r.t
k-D, such that no collection of
k-Ds is
n-D, exactly because a collection is a complex (
k-D AND
n-D) (the existence of Many is a complex result of Non-locality\Locality Linkage).
Now please read again
http://www.internationalskeptics.com/forums/showpost.php?p=5278829&postcount=6664 .