منابع مشابه
Well - Quasi - Orders Christian
Based on Isabelle/HOL’s type class for preorders, we introduce a type class for well-quasi-orders (wqo) which is characterized by the absence of “bad” sequences (our proofs are along the lines of the proof of Nash-Williams [1], from which we also borrow terminology). Our main results are instantiations for the product type, the list type, and a type of finite trees, which (almost) directly foll...
متن کاملWell-Quasi-Orders
Based on Isabelle/HOL’s type class for preorders, we introduce a type class for well-quasi-orders (wqo) which is characterized by the absence of “bad” sequences (our proofs are along the lines of the proof of Nash-Williams [1], from which we also borrow terminology). Our main results are instantiations for the product type, the list type, and a type of finite trees, which (almost) directly foll...
متن کاملWell orders in the transfinite Japaridze algebra II: Turing progressions and their well-orders
This paper is a follow up to [9, 8] and studies the poly-modal provability logics GLPΛ and natural well-founded orders therein. For each ordinal Λ one can define a propositional provability logic GLPΛ that has for each α < Λ a modal operator [α] corresponding to provability and with a dual operator 〈α〉 corresponding to consistency. By GLP we denote that class size logic that has a modality for ...
متن کاملOn Well Quasi Orders of Free Monoids
The paper investigates down-sets associated to well quasi orders. Of particular language-theoretic interest is the quasi order u s v (resp.u P v) of u being a subword (resp. a Parikh subword) of v, as well as their inverses. We establish a number of results about the regularity and e ective regularity of the down-sets, in particular, a general condition for the e ective regularity of the down-s...
متن کاملA new characterization of $L_2(q)$ by the largest element orders
We characterize the finite simple groups $L_2(q)$ by the group orders and the largest element orders, where $q$ is a prime or $q=2^a$, with $2^a+1$ or $2^a-1$ a prime.
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ژورنال
عنوان ژورنال: Fundamenta Mathematicae
سال: 1981
ISSN: 0016-2736,1730-6329
DOI: 10.4064/fm-111-1-71-76