Lasse Nielsen

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We present a new sound and complete axiomatization of regular expression containment. It consists of the conventional axiomatization of concatenation, alternation, empty set and (the singleton set containing) the empty string as an idempotent semiring, the fixed- point rule <i>E</i>* = 1 + <i>E</i> &#215; <i>E</i>* for Kleene-star, and a general coinduction(More)
Regular expression parsing is the problem of producing a parse tree of a string for a given regular expression. We show that a compact bit representation of a parse tree can be produced efficiently, in time linear in the product of input string size and regular expression size, by simplifying the DFA-based parsing algorithm due to Dubé and Feeley to emit(More)
This paper introduces a new theory of multiparty session types based on symmetric sum types, by which we can type non-deterministic orchestration choice behaviours. While the original branching type in session types can represent a choice made by a single participant and accepted by others determining how the session proceeds, the symmetric sum type(More)
In recent works, Shlomi Segall suggests and defends a luck egalitarian approach to justice in health. Concurring with G. A. Cohen's mature position he defends the idea that people should be compensated for "brute luck", i.e. the outcome of actions that it would be unreasonable to expect them to avoid. In his defense of the luck egalitarian approach he seeks(More)
This paper proposes a new theory of multiparty session types with assertions based on symmetric sum types and demonstrates its applicability to collaborative workflows in healthcare systems for clinical practice guidelines (CPGs). The theory leads to a model-driven implementation of a prototype tool for CPGs which automatically generates deadlock-free(More)
We present new algorithms for producing greedy parses for regular expressions (REs) in a semi-streaming fashion. Our lean-log algorithm executes in time O(mn) for REs of size m and input strings of size n and outputs a compact bit-coded parse tree representation. It improves on previous algorithms by: operating in only 2 passes; using only O(m) words of(More)
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