8 research outputs found
The algebra of adjacency patterns: Rees matrix semigroups with reversion
We establish a surprisingly close relationship between universal Horn classes
of directed graphs and varieties generated by so-called adjacency semigroups
which are Rees matrix semigroups over the trivial group with the unary
operation of reversion. In particular, the lattice of subvarieties of the
variety generated by adjacency semigroups that are regular unary semigroups is
essentially the same as the lattice of universal Horn classes of reflexive
directed graphs. A number of examples follow, including a limit variety of
regular unary semigroups and finite unary semigroups with NP-hard variety
membership problems.Comment: 30 pages, 9 figure
Clarifying the origin of near-infrared electroluminescence peaks for nanocrystalline germanium in metal-insulator-silicon structures
10.1063/1.1793348Applied Physics Letters85122349-2351APPL
Mapping of γ/δ T cells reveals Vδ2+ T cells resistance to senescence
10.1016/j.ebiom.2018.11.053EBioMedicine3944-5