Information About

Quasifield





DEFINITION


A quasifield (Q,+,.) is a structure, where + and . binary operations on Q, satisfying these axioms :

  • (Q,+) is a Group

  • (Q_{0},.) is a Loop

  • a.(b+c)=a.b+a.c \ orall a,b,c \in Q

  • a.x=b.x+c has exactly one solution orall a,b,c \in Q


Sometimes right distributivity is assumed instead.

Although not assumed, one can prove that the axioms imply that the additive group (Q,+) is abelian.


KERNEL


The kernel K of a quasifield Q is the set of all elements k such that :
  • a.(b.c)=(a.b).c \ orall a,b,c\in Q

  • (a+b).k=(a.k)+(b.k)\ orall a,b\in Q


Restricting the binary operations + and . to K, one can shown that (K,+,.) is a Division Ring .

One can now make a vector space of Q over K, with the following scalar multiplication :
v \otimes l = v . l\ orall v\in Q,l\in K

As the order of any finite division ring is a Prime Power , this means that the order of any quasifield is also a prime power.


PROJECTIVE PLANES


We define a ternary map T from Q to Q:
T(a,b,c)=a.b+c \ orall a,b,c\in Q

One can verify now that (Q,T) satisfies the axioms of a Planar Ternary Ring .

Thus, given a quasifield, one can always construct a Projective Plane . If it is not a division ring, the plane is never desarguesian. However, as the order of a quasifield is always a prime power, one cannot expect to find counterexamples for the conjecture that the order of a projective plane is always a prime power.

Projective planes constructed in this way have a unique geometric property : they are the only translation planes.