Displaying similar documents to “Bounded projections in weighted function spaces in a generalized unit disc”

About the decision of reachability for register machines

Véronique Cortier (2002)

RAIRO - Theoretical Informatics and Applications - Informatique Théorique et Applications

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We study the decidability of the following problem: given p affine functions f 1 , ... , f p over ℕ k and two vectors v 1 , v 2 ∈ ℕ k , is v 2 reachable from v 1 by successive iterations of f 1 , ... , f p (in this given order)? We show that this question is decidable for p = 1 , 2 and undecidable for some fixed p .

On powers of Lindelöf spaces

Isaac Gorelic (1994)

Commentationes Mathematicae Universitatis Carolinae

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We present a forcing construction of a Hausdorff zero-dimensional Lindelöf space X whose square X 2 is again Lindelöf but its cube X 3 has a closed discrete subspace of size 𝔠 + , hence the Lindelöf degree L ( X 3 ) = 𝔠 + . In our model the Continuum Hypothesis holds true. After that we give a description of a forcing notion to get a space X such that L ( X n ) = ℵ 0 for all positive integers n , but L ( X ℵ 0 ) = 𝔠 + = ℵ 2 .