Abbreviation: CAα
A \emph{cylindric algebra} of dimension α is a Boolean algebra with operators A=⟨A,∨,0,∧,1,−,ci,dij:i,j<α⟩ such that for all i,j<α
the ci are increasing: x≤cix
the ci semi-distribute over ∧: ci(x∧ciy)=cix∧ciy
the ci commute: cicjx=cjcix
the diagonals dii equal the top element: dii=1
dij=ck(dik∧dkj) for k≠i,j
ci(dij∧x)∧ci(dij∧−x)=0 for i≠j
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It is not unusual to give several (equivalent) definitions. Ideally, one of the definitions would give an irredundant axiomatization that does not refer to other classes.
Let A and B be … . A morphism from A to B is a function h:A→B that is a homomorphism: h(x…y)=h(x)…h(y)
An \emph{…} is a structure A=⟨A,…⟩ of type ⟨…⟩ such that
… is …: axiom
… is …: axiom
Example 1:
Feel free to add or delete properties from this list. The list below may contain properties that are not relevant to the class that is being described.
Classtype | variety |
---|---|
Equational theory | undecidable for α≥3, decidable otherwise |
Quasiequational theory | |
First-order theory | |
Locally finite | no |
Residual size | unbounded |
Congruence distributive | yes |
Congruence modular | yes |
Congruence n-permutable | yes, n=2 |
Congruence regular | yes |
Congruence uniform | yes |
Congruence extension property | yes |
Definable principal congruences | |
Equationally def. pr. cong. | |
Amalgamation property | |
Strong amalgamation property | |
Epimorphisms are surjective |
$\begin{array}{lr}
f(1)= &1\\ f(2)= &\\ f(3)= &\\ f(4)= &\\ f(5)= &\\
\end{array}\begin{array}{lr}
f(6)= &\\ f(7)= &\\ f(8)= &\\ f(9)= &\\ f(10)= &\\
\end{array}$
[[Representable cylindric algebras]] subvariety
[[Diagonal free cylindric algebras]] subreduct
[[Two-dimensional cylindric algebras]] subreduct