2,412 research outputs found
The (B) conjecture for uniform measures in the plane
We prove that for any two centrally-symmetric convex shapes , the function is log-concave. This
extends a result of Cordero-Erausquin, Fradelizi and Maurey in the two
dimensional case. Possible relaxations of the condition of symmetry are
discussed.Comment: 10 page
A Faithful Semantics for Generalised Symbolic Trajectory Evaluation
Generalised Symbolic Trajectory Evaluation (GSTE) is a high-capacity formal
verification technique for hardware. GSTE uses abstraction, meaning that
details of the circuit behaviour are removed from the circuit model. A
semantics for GSTE can be used to predict and understand why certain circuit
properties can or cannot be proven by GSTE. Several semantics have been
described for GSTE. These semantics, however, are not faithful to the proving
power of GSTE-algorithms, that is, the GSTE-algorithms are incomplete with
respect to the semantics.
The abstraction used in GSTE makes it hard to understand why a specific
property can, or cannot, be proven by GSTE. The semantics mentioned above
cannot help the user in doing so. The contribution of this paper is a faithful
semantics for GSTE. That is, we give a simple formal theory that deems a
property to be true if-and-only-if the property can be proven by a GSTE-model
checker. We prove that the GSTE algorithm is sound and complete with respect to
this semantics
What are logical notions?
In this manuscript, published here for the first time, Tarski explores the concept of logical notion. He draws on Klein's Erlanger Programm to locate the logical notions of ordinary geometry as those invariant under all transformations of space. Generalizing, he explicates the concept of logical notion of an arbitrary disciplin
Comparing theories: the dynamics of changing vocabulary. A case-study in relativity theory
There are several first-order logic (FOL) axiomatizations of special
relativity theory in the literature, all looking essentially different but
claiming to axiomatize the same physical theory. In this paper, we elaborate a
comparison, in the framework of mathematical logic, between these FOL theories
for special relativity. For this comparison, we use a version of mathematical
definability theory in which new entities can also be defined besides new
relations over already available entities. In particular, we build an
interpretation of the reference-frame oriented theory SpecRel into the
observationally oriented Signalling theory of James Ax. This interpretation
provides SpecRel with an operational/experimental semantics. Then we make
precise, "quantitative" comparisons between these two theories via using the
notion of definitional equivalence. This is an application of logic to the
philosophy of science and physics in the spirit of Johan van Benthem's work.Comment: 27 pages, 8 figures. To appear in Springer Book series Trends in
Logi
Static Analysis of Run-Time Errors in Embedded Real-Time Parallel C Programs
We present a static analysis by Abstract Interpretation to check for run-time
errors in parallel and multi-threaded C programs. Following our work on
Astr\'ee, we focus on embedded critical programs without recursion nor dynamic
memory allocation, but extend the analysis to a static set of threads
communicating implicitly through a shared memory and explicitly using a finite
set of mutual exclusion locks, and scheduled according to a real-time
scheduling policy and fixed priorities. Our method is thread-modular. It is
based on a slightly modified non-parallel analysis that, when analyzing a
thread, applies and enriches an abstract set of thread interferences. An
iterator then re-analyzes each thread in turn until interferences stabilize. We
prove the soundness of our method with respect to the sequential consistency
semantics, but also with respect to a reasonable weakly consistent memory
semantics. We also show how to take into account mutual exclusion and thread
priorities through a partitioning over an abstraction of the scheduler state.
We present preliminary experimental results analyzing an industrial program
with our prototype, Th\'es\'ee, and demonstrate the scalability of our
approach
On the Failure of Fixed-Point Theorems for Chain-complete Lattices in the Effective Topos
In the effective topos there exists a chain-complete distributive lattice
with a monotone and progressive endomap which does not have a fixed point.
Consequently, the Bourbaki-Witt theorem and Tarski's fixed-point theorem for
chain-complete lattices do not have constructive (topos-valid) proofs
Distance k-Sectors Exist
The bisector of two nonempty sets P and Q in a metric space is the set of all
points with equal distance to P and to Q. A distance k-sector of P and Q, where
k is an integer, is a (k-1)-tuple (C_1, C_2, ..., C_{k-1}) such that C_i is the
bisector of C_{i-1} and C_{i+1} for every i = 1, 2, ..., k-1, where C_0 = P and
C_k = Q. This notion, for the case where P and Q are points in Euclidean plane,
was introduced by Asano, Matousek, and Tokuyama, motivated by a question of
Murata in VLSI design. They established the existence and uniqueness of the
distance trisector in this special case. We prove the existence of a distance
k-sector for all k and for every two disjoint, nonempty, closed sets P and Q in
Euclidean spaces of any (finite) dimension, or more generally, in proper
geodesic spaces (uniqueness remains open). The core of the proof is a new
notion of k-gradation for P and Q, whose existence (even in an arbitrary metric
space) is proved using the Knaster-Tarski fixed point theorem, by a method
introduced by Reem and Reich for a slightly different purpose.Comment: 10 pages, 5 figure
Connections between Relation Algebras and Cylindric Algebras
Abstract. We give an informal description of a recursive representability-preserving reduction of relation algebras to cylindric algebras.
Uniform Substitution for Differential Game Logic
This paper presents a uniform substitution calculus for differential game
logic (dGL). Church's uniform substitutions substitute a term or formula for a
function or predicate symbol everywhere. After generalizing them to
differential game logic and allowing for the substitution of hybrid games for
game symbols, uniform substitutions make it possible to only use axioms instead
of axiom schemata, thereby substantially simplifying implementations. Instead
of subtle schema variables and soundness-critical side conditions on the
occurrence patterns of logical variables to restrict infinitely many axiom
schema instances to sound ones, the resulting axiomatization adopts only a
finite number of ordinary dGL formulas as axioms, which uniform substitutions
instantiate soundly. This paper proves soundness and completeness of uniform
substitutions for the monotone modal logic dGL. The resulting axiomatization
admits a straightforward modular implementation of dGL in theorem provers
A Proof of Tarski’s Fixed Point Theorem by Application of Galois Connections
Two examples of Galois connections and their dual forms are considered. One
of them is applied to formulate a criterion when a given subset of a complete lattice forms
a complete lattice. The second, closely related to the first, is used to prove in a short way
the Knaster-Tarski’s fixed point theore
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