Zobrazeno 1 - 10
of 233
pro vyhledávání: '"Lipparini Paolo"'
Autor:
Lipparini, Paolo
A specialization semilattice is a semilattice together with a coarser preorder satisfying a compatibility condition. We show that the category of specialization semilattices is isomorphic to the category of semilattices with a congruence, hence equiv
Externí odkaz:
http://arxiv.org/abs/2407.08446
Autor:
Lipparini, Paolo
We present a definition for the sum of a sequence of combinatorial games. This sum coincides with the classical sum in the case of a converging sequence of real numbers and with the infinitary natural sum in the case of a sequence of ordinal numbers.
Externí odkaz:
http://arxiv.org/abs/2406.02453
Autor:
Lipparini, Paolo
We show that a variety with J\'onsson terms $t_1, \dots, t_{n-1}$ has directed J\'onsson terms $d_1, \dots, d_{n-1}$, for the same value of the indices. Refined results are obtained for locally finite varieties.
Comment: 15 pages
Comment: 15 pages
Externí odkaz:
http://arxiv.org/abs/2405.02768
Autor:
Lipparini Paolo
Publikováno v:
Annales Mathematicae Silesianae, Vol 32, Iss 1, Pp 247-262 (2018)
We study a countably infinite iteration of the natural product between ordinals.We present an “effective” way to compute this countable natural product; in the non trivial cases the result depends only on the natural sum of the degrees of the fac
Externí odkaz:
https://doaj.org/article/774b8a8663c34dcb8fdcbd8c4f74da55
Autor:
Lipparini, Paolo
We show that the class of Contact join-semilattices, as introduced by T. Ivanova, is not finitely axiomatizable. On the other hand, a simple finite axiomatization exists for the class of those join semilattices with a weak contact relation which can
Externí odkaz:
http://arxiv.org/abs/2311.12599
Autor:
Lipparini, Paolo
We characterize those join semilattices with a multicontact relation which can be embedded into (the reduct of) a Boolean algebra with multicontact given by overlap, equivalently, into a distributive lattice with additive multicontact, still equivale
Externí odkaz:
http://arxiv.org/abs/2308.04874
Autor:
Lipparini, Paolo
We provide optimal bounds for $\alpha (\beta \circ \gamma \circ \dots )$ in $4$-distributive varieties, as well as some further partial generalizations.
Comment: 9 pages
Comment: 9 pages
Externí odkaz:
http://arxiv.org/abs/2308.04532
Autor:
Freese, Ralph, Lipparini, Paolo
Publikováno v:
Algebra Universalis 85, 11 (2024)
We show that for a large class of varieties of algebras, the equational theory of the congruence lattices of the members is not finitely based.
Comment: 18 pages
Comment: 18 pages
Externí odkaz:
http://arxiv.org/abs/2306.14396
Autor:
Lipparini, Paolo
We devise exact conditions under which a join semilattice with a weak contact relation can be semilattice embedded into a Boolean algebra with an overlap contact relation, equivalently, into a distributive lattice with additive contact relation. A si
Externí odkaz:
http://arxiv.org/abs/2303.06787
Autor:
Lipparini, Paolo
We study contact posets and show that every contact poset can be embedded into a Boolean poset with overlap contact relation. Contact posets and (nonadditive) contact semilattices have the superamalgamation property, Fra\"\i ss\'e limits and model co
Externí odkaz:
http://arxiv.org/abs/2303.06259