Primitive Skew Lattices
Skew lattices consisting of exactly two D-classes are called primitive skew lattices. Given such a skew lattice with -classes in, then for any and, the subsets
{} and {}
are called, respectively, cosets of A in B and cosets of B in A. These cosets partition B and A with and . Cosets are always rectangular subalgebras in their -classes. What is more, the partial order induces a coset bijection defined by:
iff, for and .
Collectively, coset bijections describe between the subsets and . They also determine and for pairs of elements from distinct -classes. Indeed, given and, let be the cost bijection between the cosets in and in . Then:
and .
In general, given and with and, then belong to a common - coset in and belong to a common -coset in if and only if . Thus each coset bijection is, in some sense, a maximal collection of mutually parallel pairs .
Every primitive skew lattice factors as the fibred product of its maximal left and right- handed primitive images . Right-handed primitive skew lattices are constructed as follows. Let and be partitions of disjoint nonempty sets and, where all and share a common size. For each pair pick a fixed bijection from onto . On and separately set and ; but given and, set
and
where and with belonging to the cell of and belonging to the cell of . The various are the coset bijections. This is illustrated in the following partial Hasse diagram where and the arrows indicate the -outputs and from and .
One constructs left-handed primitive skew lattices in dual fashion. All right handed primitive skew lattices can be constructed in this fashion. (See Section 1.)
Read more about this topic: Skew Lattice
Famous quotes containing the word primitive:
“Children cant make their own rules and no child is happy without them. The great need of the young is for authority that protects them against the consequences of their own primitive passions and their lack of experience, that provides with guides for everyday behavior and that builds some solid ground they can stand on for the future.”
—Leontine Young (20th century)