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Curvature in image and shape processing

Yonathan Aflalo, Anastasia Dubrovina, Ron Kimmel, Aaron Wetzler (2013)

Actes des rencontres du CIRM

The laplacian operator applied to the coordinates of a manifold provides the mean curvature vector. Manipulating the metric of the manifold or interpreting its coordinates in various ways provide useful tools for shape and image processing and representation. We will review some of these tools focusing on scale invariant geometry, curvature flow with respect to an embedding of the image manifold in a high dimensional space, and object segmentation by active contours defined via the shape laplacian...

Curve cuspless reconstruction via sub-riemannian geometry

Ugo Boscain, Remco Duits, Francesco Rossi, Yuri Sachkov (2014)

ESAIM: Control, Optimisation and Calculus of Variations

We consider the problem of minimizing 0 ξ 2 + K 2 ( s ) d s ∫ 0 ℓ ξ 2 + K 2 ( s )   d s for a planar curve having fixed initial and final positions and directions. The total lengthℓ is free. Here s is the arclength parameter, K(s) is the curvature of the curve and ξ > 0 is a fixed constant. This problem comes from a model of geometry of vision due to Petitot, Citti and Sarti. We study existence of local and global minimizers for this problem. We prove that if for a certain choice of boundary conditions there...

Decidability of code properties

Henning Fernau, Klaus Reinhardt, Ludwig Staiger (2007)

RAIRO - Theoretical Informatics and Applications

We explore the borderline between decidability and undecidability of the following question: “Let C be a class of codes. Given a machine 𝔐 of type X, is it decidable whether the language L ( 𝔐 ) lies in C or not?” for codes in general, ω-codes, codes of finite and bounded deciphering delay, prefix, suffix and bi(pre)fix codes, and for finite automata equipped with different versions of push-down stores and counters.

Deciding knowledge in security protocols under some e-voting theories

Mouhebeddine Berrima, Narjes Ben Rajeb, Véronique Cortier (2011)

RAIRO - Theoretical Informatics and Applications - Informatique Théorique et Applications

In the last decade, formal methods have proved their interest when analyzing security protocols. Security protocols require in particular to reason about the attacker knowledge. Two standard notions are often considered in formal approaches: deducibility and indistinguishability relations. The first notion states whether an attacker can learn the value of a secret, while the latter states whether an attacker can notice some difference between protocol runs with different values of the secret. Several...

Deciding knowledge in security protocols under some e-voting theories

Mouhebeddine Berrima, Narjes Ben Rajeb, Véronique Cortier (2011)

RAIRO - Theoretical Informatics and Applications

In the last decade, formal methods have proved their interest when analyzing security protocols. Security protocols require in particular to reason about the attacker knowledge. Two standard notions are often considered in formal approaches: deducibility and indistinguishability relations. The first notion states whether an attacker can learn the value of a secret, while the latter states whether an attacker can notice some difference between protocol runs with different values of the secret. Several...

Decomposition of vibration signals into deterministic and nondeterministic components and its capabilities of fault detection and identification

Tomasz Barszcz (2009)

International Journal of Applied Mathematics and Computer Science

The paper investigates the possibility of decomposing vibration signals into deterministic and nondeterministic parts, based on the Wold theorem. A short description of the theory of adaptive filters is presented. When an adaptive filter uses the delayed version of the input signal as the reference signal, it is possible to divide the signal into a deterministic (gear and shaft related) part and a nondeterministic (noise and rolling bearings) part. The idea of the self-adaptive filter (in the literature...

Decomposition-based logic synthesis for PAL-based CPLDs

Adam Opara, Dariusz Kania (2010)

International Journal of Applied Mathematics and Computer Science

The paper presents one concept of decomposition methods dedicated to PAL-based CPLDs. The proposed approach is an alternative to the classical one, which is based on two-level minimization of separate single-output functions. The key idea of the algorithm is to search for free blocks that could be implemented in PAL-based logic blocks containing a limited number of product terms. In order to better exploit the number of product terms, two-stage decomposition and BDD-based decomposition are to be...

Dedicated spectral method of Boolean function decomposition

Piotr Porwik, Radomir Stankovic (2006)

International Journal of Applied Mathematics and Computer Science

Spectral methods constitute a useful tool in the analysis and synthesis of Boolean functions, especially in cases when other methods reduce to brute-force search procedures. There is renewed interest in the application of spectral methods in this area, which extends also to the closely connected concept of the autocorrelation function, for which spectral methods provide fast calculation algorithms. This paper discusses the problem of spectral decomposition of Boolean functions using the Walsh transform...

Depth lower bounds for monotone semi-unbounded fan-in circuits

Jan Johannsen (2001)

RAIRO - Theoretical Informatics and Applications - Informatique Théorique et Applications

The depth hierarchy results for monotone circuits of Raz and McKenzie [5] are extended to the case of monotone circuits of semi-unbounded fan-in. It follows that the inclusions N C i S A C i A C i are proper in the monotone setting, for every i 1 .

Depth Lower Bounds for Monotone Semi-Unbounded Fan-in Circuits

Jan Johannsen (2010)

RAIRO - Theoretical Informatics and Applications

The depth hierarchy results for monotone circuits of Raz and McKenzie [5] are extended to the case of monotone circuits of semi-unbounded fan-in. It follows that the inclusions NCi ⊆ SACi ⊆ ACi are proper in the monotone setting, for every i ≥ 1.

Design of mealy finite-state machines with the transformation of object codes

Alexander Barkalov, Alexander Barkalov (2005)

International Journal of Applied Mathematics and Computer Science

An optimization method of the logic circuit of a Mealy finite-state machine is proposed. It is based on the transformation of object codes. The objects of the Mealy FSM are internal states and sets of microoperations. The main idea is to express the states as some functions of sets of microoperations (internal states) and tags. The application of this method is connected with the use of a special code converter in the logic circuit of an FSM. An example of application is given. The effectiveness...

Detection of influential points by convex hull volume minimization

Petr Tichavský, Pavel Boček (1998)

Kybernetika

A method of geometrical characterization of multidimensional data sets, including construction of the convex hull of the data and calculation of the volume of the convex hull, is described. This technique, together with the concept of minimum convex hull volume, can be used for detection of influential points or outliers in multiple linear regression. An approximation to the true concept is achieved by ordering the data into a linear sequence such that the volume of the convex hull of the first...

Currently displaying 361 – 380 of 1507