Ulrich Schöpp

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We consider the problem of providing formal support for working with abstract syntax involving variable binders. Gabbay and Pitts have shown in their work on Fraenkel-Mostowski (FM) set theory how to address this through first-class names: in this paper we present a dependent type theory for programming and reasoning with such names. Our development is(More)
Names and name-binding are useful concepts in the theory and practice of formal systems. In this thesis we study them in the context of dependent type theory. We propose a novel dependent type theory with primitives for the explicit handling of names. As the main application, we consider programming and reasoning with abstract syntax involving variable(More)
We present a sequent calculus for formally verifying modal μ-calculus properties of concurrent processes. Building on work by Dam and Gurov, the proof system contains rules for the explicit manipulation of fixed-point approximants. We develop a new syntax for approximants, incorporating, in particular, modalities for approximant modification. We make(More)
Pointer programs are a model of structured computation within LOGSPACE. They capture the common description of LOGSPACE algorithms as programs that take as input some structured data (e.g. a graph) and that store in memory only a constant number of pointers to the input (e.g. to the graph nodes). In this paper we study undirected s-t-reachability for a(More)
A number of complexity classes, most notably PTIME, have been characterised by sub-systems of linear logic. In this paper we show that the functions computable in logarithmic space can also be characterised by a restricted version of linear logic. We introduce stratified bounded affine logic (SBAL), a restricted version of bounded linear logic, in which not(More)
We consider the problem of functional programming with data in external memory, in particular as it appears in sublinear space computation. Writing programs with sublinear space usage often requires one to use special implementation techniques for otherwise easy tasks, e.g. one cannot compose functions directly for lack of space for the intermediate result,(More)
Type systems that allow control over low-level compilation details have been developed in the context of resource aware compilation, e.g. for circuit synthesis or for programming with logarithmic space. It was recently observed that some compilation techniques developed in this context, while motivated by capturing certain resource usage restrictions, are(More)
We propose a semantics for the ∇-quantifier of Miller and Tiu. First we consider the case for classical first-order logic. In this case, the interpretation is close to standard Tarski-semantics and completeness can be shown using a standard argument. Then we put our semantics into a broader context by giving a general interpretation of ∇ in categories with(More)