Monadic Logic of Order over Naturals has no Finite Base

2002 ◽  
Vol 12 (2) ◽  
pp. 243-253 ◽  
Author(s):  
D. Beauquier
Keyword(s):  
Finite Base ◽  
Monadic Logic

scholarly journals Finite representability of semigroups with demonic refinement

2021 ◽  
Vol 82 (2) ◽  
Author(s):  
Robin Hirsch ◽  
Jaš Šemrl
Keyword(s):  
Partial Order ◽  
Turing Machines ◽  
Binary Relations ◽  
Finite Representation ◽  
First Order ◽  
Finite Structures ◽  
Finite Base ◽  
Finite Set ◽  
Finite Representability ◽  
Representation Class

AbstractThe motivation for using demonic calculus for binary relations stems from the behaviour of demonic turing machines, when modelled relationally. Relational composition (; ) models sequential runs of two programs and demonic refinement ($$\sqsubseteq $$ ⊑ ) arises from the partial order given by modeling demonic choice ($$\sqcup $$ ⊔ ) of programs (see below for the formal relational definitions). We prove that the class $$R(\sqsubseteq , ;)$$ R ( ⊑ , ; ) of abstract $$(\le , \circ )$$ ( ≤ , ∘ ) structures isomorphic to a set of binary relations ordered by demonic refinement with composition cannot be axiomatised by any finite set of first-order $$(\le , \circ )$$ ( ≤ , ∘ ) formulas. We provide a fairly simple, infinite, recursive axiomatisation that defines $$R(\sqsubseteq , ;)$$ R ( ⊑ , ; ) . We prove that a finite representable $$(\le , \circ )$$ ( ≤ , ∘ ) structure has a representation over a finite base. This appears to be the first example of a signature for binary relations with composition where the representation class is non-finitely axiomatisable, but where the finite representation property holds for finite structures.

scholarly journals Applying Set Theory E88

Axioms ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 329
Author(s):  
Saharon Shelah
Keyword(s):  
Set Theory ◽  
Model Theory ◽  
Real Line ◽  
Cantor Sets ◽  
General Topology ◽  
The Real ◽  
Collectionwise Hausdorff ◽  
Monadic Logic

We prove some results in set theory as applied to general topology and model theory. In particular, we study ℵ1-collectionwise Hausdorff, Chang Conjecture for logics with Malitz-Magidor quantifiers and monadic logic of the real line by odd/even Cantor sets.

The characterization of monadic logic

1973 ◽  
Vol 38 (3) ◽  
pp. 481-488 ◽  
Author(s):  
Leslie H. Tharp
Keyword(s):  
Finite Sequence ◽  
Higher Order ◽  
Predicate Calculus ◽  
Intrinsic Properties ◽  
Monadic Logic

The first section of this paper is concerned with the intrinsic properties of elementary monadic logic (EM), and characterizations in the spirit of Lindström [2] are given. His proofs do not apply to monadic logic since relations are used, and intrinsic properties of EM turn out to differ in certain ways from those of the elementary logic of relations (i.e., the predicate calculus), which we shall call EL. In the second section we investigate connections between higher-order monadic and polyadic logics.EM is the subsystem of EL which results by the restriction to one-place predicate letters. We omit constants (for simplicity) but take EM to contain identity. Let a type be any finite sequence (possibly empty) of one-place predicate letters. A model M of type has a nonempty universe ∣M∣ and assigns to each predicate letter P of a subset PM of ∣M∣.Let us take a monadic logic L to be any collection of classes of models, called L-classes, satisfying the following:1. All models in a given L-class are of the same type (called the type of the class).2. Isomorphic models lie in the same L-classes.3. If and are L-classes of the same type, then and are L-classes.

scholarly journals Geometry of the Kahan discretizations of planar quadratic Hamiltonian systems

2019 ◽  
Vol 475 (2223) ◽  
pp. 20180761 ◽  
Author(s):  
Matteo Petrera ◽  
Jennifer Smirin ◽  
Yuri B. Suris
Keyword(s):  
Vector Field ◽  
Base Point ◽  
Hamiltonian Vector ◽  
Geometric Condition ◽  
Hamiltonian Vector Field ◽  
Cubic Curves ◽  
Birational Map ◽  
Base Points ◽  
Finite Base ◽  
Pass Through

Kahan discretization is applicable to any quadratic vector field and produces a birational map which approximates the shift along the phase flow. For a planar quadratic canonical Hamiltonian vector field, this map is known to be integrable and to preserve a pencil of cubic curves. Generically, the nine base points of this pencil include three points at infinity (corresponding to the asymptotic directions of cubic curves) and six finite points lying on a conic. We show that the Kahan discretization map can be represented in six different ways as a composition of two Manin involutions, corresponding to an infinite base point and to a finite base point. As a consequence, the finite base points can be ordered so that the resulting hexagon has three pairs of parallel sides which pass through the three base points at infinity. Moreover, this geometric condition on the base points turns out to be characteristic: if it is satisfied, then the cubic curves of the corresponding pencil are invariant under the Kahan discretization of a planar quadratic canonical Hamiltonian vector field.

Equational properties of fixed-point operations in cartesian categories: An overview

2019 ◽  
Vol 29 (06) ◽  
pp. 909-925
Author(s):  
Z Ésik
Keyword(s):  
Fixed Point ◽  
Equational Theory ◽  
Continuous Functions ◽  
Equivalence Classes ◽  
Finitely Based ◽  
Additive Structure ◽  
Complete Lattices ◽  
Finite Base ◽  
Language Equivalence ◽  
Context Free

AbstractSeveral fixed-point models share the equational properties of iteration theories, or iteration categories, which are cartesian categories equipped with a fixed point or dagger operation subject to certain axioms. After discussing some of the basic models, we provide equational bases for iteration categories and offer an analysis of the axioms. Although iteration categories have no finite base for their identities, there exist finitely based implicational theories that capture their equational theory. We exhibit several such systems. Then we enrich iteration categories with an additive structure and exhibit interesting cases where the interaction between the iteration category structure and the additive structure can be captured by a finite number of identities. This includes the iteration category of monotonic or continuous functions over complete lattices equipped with the least fixed-point operation and the binary supremum operation as addition, the categories of simulation, bisimulation, or language equivalence classes of processes, context-free languages, and others. Finally, we exhibit a finite equational system involving residuals, which is sound and complete for monotonic or continuous functions over complete lattices in the sense that it proves all of their identities involving the operations and constants of cartesian categories, the least fixed-point operation and binary supremum, but not involving residuals.

The Infinite Commitment of Finite Minds

1984 ◽  
Vol 14 (2) ◽  
pp. 235-255 ◽  
Author(s):  
Timothy Williamson
Keyword(s):  
Finite Axiomatization ◽  
Semantic Constraint ◽  
Theory Of Meaning ◽  
Finite Base ◽  
Finite Minds

Chomsky (in syntax) and Davidson (in semantics) have made much of the constraint that speakers’ competence must have a finite base. This base is often supposed to mean a finite axiomatization of beliefs. Section I shows why this is plausible. Section II shows why it is wrong. Section III shows why the semantic constraint is thereby trivialized.'Finite minds cannot have infinitely many beliefs’ has been taken for a useful truism. A theory of meaning, say, for a language may, for each of its infinitely many sentences, attribute to competent speakers knowledge, in some sense, and so in a corresponding sense belief, about the meaning (or some substitute for it) of that sentence. Our truism seems to force this paradox to immediate and constructive resolution: as finite minds we have a finite view on our language that recognizably entails an infinity of propositions about it.

scholarly journals On the Existence of a Finite Base for Complete Trace Equivalence over BPA with Interrupt

2007 ◽  
Vol 14 (5) ◽  
Author(s):  
Luca Aceto ◽  
Silvio Capobianco ◽  
Anna Ingólfsdóttir
Keyword(s):  
Process Algebra ◽  
Basic Process ◽  
Single Action ◽  
Finite Axiomatization ◽  
Finite Base ◽  
Special Case ◽  
Trace Equivalence

We study Basic Process Algebra with interrupt modulo complete trace equivalence. We show that, unlike in the setting of the more demanding bisimilarity, a ground complete finite axiomatization exists. We explicitly give such an axiomatization, and extend it to a finite complete one in the special case when a single action is present.

scholarly journals Monadic Bounded Algebras

2021 ◽  
Author(s):  
◽  
Galym Akishev
Keyword(s):  
Upper Bound ◽  
Subdirect Product ◽  
Completeness Theorem ◽  
Finitely Generated ◽  
Algebraic Version ◽  
Finite Set ◽  
Monadic Logic ◽  
Object Of Study ◽  
Bounded Graph

<p>The object of study of the thesis is the notion of monadic bounded algebras (shortly, MBA's). These algebras are motivated by certain natural constructions in free (first-order) monadic logic and are related to free monadic logic in the same way as monadic algebras of P. Halmos to monadic logic (Chapter 1). Although MBA's come from logic, the present work is in algebra. Another important way of approaching MBA's is via bounded graphs, namely, the complex algebra of a bounded graph is an MBA and vice versa. The main results of Chapter 2 are two representation theorems: 1) every model is a basic MBA and every basic MBA is isomorphic to a model; 2) every MBA is isomorphic to a subdirect product of basic MBA's. As a consequence, every MBA is isomorphic to a subdirect product of models. This result is thought of as an algebraic version of semantical completeness theorem for free monadic logic. Chapter 3 entirely deals with MBA-varieties. It is proved by the method of filtration that every MBA-variety is generated by its finite special members. Using connections in terms of bounded morphisms among certain bounded graphs, it is shown that every MBA-variety is generated by at most three special (not necessarily finite) MBA's. After that each MBA-variety is equationally characterized. Chapter 4 considers finitely generated MBA's. We prove that every finitely generated MBA is finite (an upper bound on the number of elements is provided) and that the number of elements of a free MBA on a finite set achieves its upper bound. Lastly, a procedure for constructing a free MBA on any finite set is given.</p>

scholarly journals DUALITY FOR COHOMOLOGY OF CURVES WITH COEFFICIENTS IN ABELIAN VARIETIES

2018 ◽  
Vol 240 ◽  
pp. 42-149 ◽  
Author(s):  
TAKASHI SUZUKI
Keyword(s):  
Function Field ◽  
Positive Characteristic ◽  
Abelian Varieties ◽  
Base Field ◽  
Tate Pairing ◽  
Global Function ◽  
Crystalline Cohomology ◽  
Local Duality ◽  
Height Pairing ◽  
Finite Base

In this paper, we formulate and prove a duality for cohomology of curves over perfect fields of positive characteristic with coefficients in Néron models of abelian varieties. This is a global function field version of the author’s previous work on local duality and Grothendieck’s duality conjecture. It generalizes the perfectness of the Cassels–Tate pairing in the finite base field case. The proof uses the local duality mentioned above, Artin–Milne’s global finite flat duality, the nondegeneracy of the height pairing and finiteness of crystalline cohomology. All these ingredients are organized under the formalism of the rational étale site developed earlier.

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