Data streams are modeled as infinite or finite sequences of data elements coming from an arbitrary but fixed universe. The universe can have various built-in functions and predicates. Stream queries are modeled as functions from streams to streams. Both timed and untimed settings are considered. Issues investigated include abstract definitions of computability of stream queries; the connection ...

A finite-time computable function is a partial function from Σ to Σ whose value is constructed by concatenating a finite list with a suffix of the argument. A finite-time computability preserving conversion α : X → Y for X,Y ⊂ Σ is a bijection which preserves finite-time computability. We show that all the finite-time computability preserving conversions with the domain Σ are extended sliding b...

This note gives a simple example of a polynomial time computable martingale that has rational values but is not exactly computable.

The strong relationship between topology and computations has played a central role in the development of several branches of theoretical computer science: foundations of functional programming, computational geometry, computability theory, computable analysis. Often it happens that a given function is not computable simply because it is not continuous. In many cases, the function can moreover ...