In the paper the existing results concerning a special kind of trajectories and the theory of first return continuous functions connected with them are used to examine some algebraic properties of classes of functions. To that end we define a new class of functions (denoted Conn) contained between the families (widely described in literature) of Darboux Baire 1 functions (DB1) and connectivity ...

The aim of this paper is to present a detailed explanation of three models of Shelah. We show the rule of the amalgamation in the construction of models in which all deenable sets of reals have Baire property or are Lebesgue measurable. Next we construct a model in which every projective set of reals has Baire property, a model with the Uniformization Property and a model of ZF + DC in which al...

We begin the fine analysis of non Borel pointclasses. Working in ZFC + ̃ 11), we describe the Wadge hierarchy of the class of increasing differences of coanalytic subsets of the Baire space by extending results obtained by Louveau ([5]) for the Borel sets. Introduction. Collections of substets of the Baire space, the "logician’s reals", that are closed under continuous preimages have always been...

In the 1970s M. Laczkovich posed the following problem: Let B1(X) denote the set of Baire class 1 functions defined on a Polish space X equipped with the pointwise ordering. Characterize the order types of the linearly ordered subsets of B1(X). The main result of the present paper is a complete solution to this problem. We prove that a linear order is isomorphic to a linearly ordered family of ...

In this paper, we show that for an almost locally separable metrizable space X, if its Wijsman hyperspace induced by one compatible metric is Baire, then X itself must be Baire. We also provide an example to demonstrate the necessity of separability.

An important problem in topology is to determine the effects on the function space of imposing some natural topological condition on the space X [5]. In this way, it is practical to characterize the complemented subalgebras of Banach algebras. In our investigation, we relate the second category property of [0,1] with certain properties of the complemented subalgebras of bounded real Baire-1 fun...