On the Pytkeev property in spaces of continuous functions

Answering a question of Sakai, we show that the minimal cardinality of a set of reals X such that C_p(X) does not have the Pytkeev property is equal to the pseudo-intersection number p. Our approach leads to a natural characterization of the Pytkeev property of C_p(X) by means of a covering property of X, and to a similar result for the Reznicenko property of C_p(X)

Palaeoecology of Valletia antiqua Favre in Joukowsky & Favre, 1913 (Bivalvia, Hippuritida, Diceratidae); with comments on the taxonomy and distribution of the genus Valletia

The early rudist bivalve Valletia antiqua Favre in Joukowsky & Favre, 1913 is recorded for the first time from the Tithonian to Berriasian Štramberk Limestone (northeastern Czech Republic) and Ernstbrunn Limestone (Lower Austria). The species is re-described and its spatial distribution and stratigraphical range are outlined. Furthermore, the palaeoecology of Valletia antiqua is discussed in the light of novel data on palaeocommunities and microfacies, habitat selection and intraspecific competition for settling space among juveniles. The study is supplemented with a commented list of all nominal species that have been assigned to Valletia, including data on type localities, type strata, and distribution.Web of Science90363261

Pseudoradial Spaces: Finite Products and an Example From CH

∗ The first named author’s research was partially supported by GAUK grant no. 350, partially by the Italian CNR. Both supports are gratefully acknowledged. The second author was supported by funds of Italian Ministery of University and by funds of the University of Trieste (40% and 60%).Aiming to solve some open problems concerning pseudoradial spaces, we shall present the following: Assuming CH, there are two semiradial spaces without semi-radial product. A new property of pseudoradial spaces insuring the pseudoradiality of a product is presented