A Common Fixed Point Theorem for Six Mappings in G-Banach Space with Weak-Compatibility

The aim of  this paper is to introduce the concept of G-Banach Space and prove a common fixed point theorem for six mappings in G-Banach spaces with weak–compatibility. Keywords: Fixed point , common fixed point , G-Banach Space , Continuous mappings , weak compatible mappings

Computing All Isolated Invariant Sets at a Finite Resolution

Conley Index theory has inspired the development of rigorous computational methods to study dynamics. These methods construct outer approximations, combinatorial representations of the system, which allow us to represent the system as a combination of two graphs over a common vertex set. Invariant sets are sets of vertices and edges on the resulting digraph. Conley Index theory relies on isolated invariant sets, which are maximal invariant sets that meet an isolation condition, to describe the dynamics of the system. In this work, we present a computationally efficient and rigorous algorithm for computing all isolated invariant sets given an outer approximation. We improve upon an existing algorithm that “grows” iso- lated invariant sets individually and requires an input size of 2n, where n is the number of grid elements used for the outer approximation

Fixed Points Theorems for Non-Transitive Relations

In this paper, we develop an Isabelle/HOL library of order-theoretic fixed-point theorems. We keep our formalization as general as possible: we reprove several well-known results about complete orders, often with only antisymmetry or attractivity, a mild condition implied by either antisymmetry or transitivity. In particular, we generalize various theorems ensuring the existence of a quasi-fixed point of monotone maps over complete relations, and show that the set of (quasi-)fixed points is itself complete. This result generalizes and strengthens theorems of Knaster-Tarski, Bourbaki-Witt, Kleene, Markowsky, Pataraia, Mashburn, Bhatta-George, and Stouti-Maaden

FICS 2010

International audienceInformal proceedings of the 7th workshop on Fixed Points in Computer Science (FICS 2010), held in Brno, 21-22 August 201

Fixed Points Theorems for Non-Transitive Relations

In this paper, we develop an Isabelle/HOL library of order-theoretic fixed-point theorems. We keep our formalization as general as possible: we reprove several well-known results about complete orders, often with only antisymmetry or attractivity, a mild condition implied by either antisymmetry or transitivity. In particular, we generalize various theorems ensuring the existence of a quasi-fixed point of monotone maps over complete relations, and show that the set of (quasi-)fixed points is itself complete. This result generalizes and strengthens theorems of Knaster-Tarski, Bourbaki-Witt, Kleene, Markowsky, Pataraia, Mashburn, Bhatta-George, and Stouti-Maaden

Proving Fixed Points

We propose a method to characterize the fixed points described in Tarski's theorem for complete lattices. The method is deductive: the least and greatest fixed points are "proved" in some inference system defined from deduction rules. We also apply the method to two other fixed point theorems, a generalization of Tarski's theorem to chain-complete posets and Bourbaki-Witt's theorem. Finally, we compare the method with the traditional iterative method resorting to ordinals and the original impredicative method used by Tarski