A \emph{Wajsberg hoop} is a hoop A=⟨A,⋅,→,1⟩ such that
(x→y)→y=(y→x)→x
Remark: Lattice operations are term-definable by x∧y=x⋅(x→y) and x∨y=(x→y)→y.
Let A and B be Wajsberg hoops. A morphism from A to B is a function h:A→B that is a homomorphism:
h(x⋅y)=h(x)⋅h(y), h(x→y)=h(x)→h(y), h(1)=1
Example 1:
Classtype | variety |
---|---|
Equational theory | decidable |
Quasiequational theory | |
First-order theory | |
Locally finite | no |
Residual size | |
Congruence distributive | yes |
Congruence modular | yes |
Congruence n-permutable |
Congruence regular & yes Radim Belohlovek, \emph{On the regularity of MV-algebras and Wajsberg hoops}, Algebra Universalis, \textbf{44}, 2000, 375–377MRreview\\\hline
f(1)=1f(2)=1f(3)=f(4)=f(5)=f(6)=f(7)=