arXiv subjects

Tim Richter

Publications and source records attributed to Tim Richter.

4 recordsLinked to original sources

arXiv2026

Pareto climate economics: optimism, pessimism and the polarization of societies

We argue that simple conceptual models of the relation between short-term efforts in climate mitigation and adaptation policies (STECM&AP) and possible climate damages can help understanding the difficulties of increasing public support for a transition towards sustainable, decarbonized economies. Specifically, we show that, under fairly general conditions, mistrust and pessimism tend to polarize support for either minimal ``business as usual'' policies or maximal ``all-in climate mitigation efforts'' choices. Under the same conditions, trust and optimism tend to de-polarize societies towards moderate climate mitigation and adaptation (CM&A) policies and promote social consensus. If the relation between short-term efforts and possible climate damages can be quantified via empirical or model data, Pareto climate economics can be applied to extend these conceptual models and support climate decision making with trustable computational methods.

cs.LO↗

arXiv2026

Optimization under uncertainty: understanding orders and testing programs with specifications

One of the most ubiquitous problems in optimization is that of finding all the elements of a finite set at which a function $f$ attains its minimum (or maximum). When the codomain of $f$ is equipped with a total order, it is easy to specify, implement, and verify generic solutions to this problem. But what if $f$ is affected by uncertainties? What if one seeks values that minimize more than one objective, or if $f$ does not return a single result but a set of possible results, or even a probability distribution? Such situations are common in climate science, economics, and engineering. Developing trustworthy solution methods for optimization under uncertainty requires formulating and answering these questions rigorously, including deciding which order relations to apply in different cases. We show how functional programming can support this task, and apply it to specify and test solution methods for cases where optimization is affected by two conceptually different kinds of uncertainty: value and functorial uncertainty. We analyze the interplay of orders in these contexts, demonstrate how standard minimization generalizes to partial orders in the multi-objective setting and how it can be lifted via monotonicity conditions to handle functorial uncertainty.

math.OC↗

arXiv2021

Extensional equality preservation and verified generic programming

In verified generic programming, one cannot exploit the structure of concrete data types but has to rely on well chosen sets of specifications or abstract data types (ADTs). Functors and monads are at the core of many applications of functional programming. This raises the question of what useful ADTs for verified functors and monads could look like. The functorial map of many important monads preserves extensional equality. For instance, if $f, g : A \rightarrow B$ are extensionally equal, that is, $\forall x \in A, \ f \ x = g \ x$, then $map \ f : List \ A \rightarrow List \ B$ and $map \ g$ are also extensionally equal. This suggests that preservation of extensional equality could be a useful principle in verified generic programming. We explore this possibility with a minimalist approach: we deal with (the lack of) extensional equality in Martin-Löf's intensional type theories without extending the theories or using full-fledged setoids. Perhaps surprisingly, this minimal approach turns out to be extremely useful. It allows one to derive simple generic proofs of monadic laws but also verified, generic results in dynamical systems and control theory. In turn, these results avoid tedious code duplication and ad-hoc proofs. Thus, our work is a contribution towards pragmatic, verified generic programming.

cs.LO↗

arXiv2018

Tracing sharing in an imperative pure calculus (Extended Version)

We introduce a type and effect system, for an imperative object calculus, which infers "sharing" possibly introduced by the evaluation of an expression, represented as an equivalence relation among its free variables. This direct representation of sharing effects at the syntactic level allows us to express in a natural way, and to generalize, widely-used notions in literature, notably "uniqueness" and "borrowing". Moreover, the calculus is "pure" in the sense that reduction is defined on language terms only, since they directly encode store. The advantage of this non-standard execution model with respect to a behaviourally equivalent standard model using a global auxiliary structure is that reachability relations among references are partly encoded by scoping.

cs.PL↗