Talk by Elisabeth Bradley, University of Colorado – Niels Bohr Institute - University of Copenhagen

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Talk by Elisabeth Bradley, University of Colorado

Forensic Paleoclimatology

In order to deduce when a moraine was formed, or to estimate the date
of the termination of the penultimate ice age, geoscientists face an
challenging forensic reasoning problem.  The data are sparse and
noisy; worse yet, the geological processes that produced those data,
and that affected them between creation and sampling, are unknown.
When a glacier folds, for instance, younger material can appear higher
up in an ice core, destroying the timeline; if a rock falls onto a
moraine from some higher scarp, its apparent age can skew the
distribution from which geoscientists deduce the landform's age.
Experts approach this kind of problem by treating it like a crime
scene and asking the question ``What physical and chemical processes
could have produced these data, and what does that say about the
timeline?''  To answer that question, scientists make some assumptions about
those processes, project those assumptions backwards through time and
space to the putative formation time of the data, and iterate the
process until the results are consistent.  Needless to say, the number
of scenarios rapidly explodes and even experts---who can quickly prune
out less likely scenarios---can get overwhelmed, as can the computers
that sling the data and run the equations that operationalize those
hypotheses.  Software support for this task is extremely limited, so
very few papers in the current literature explore the space of
possibilities very broadly.  I will talk about two automated reasoning
tools---one complete and one under development---that employ an
argumentation engine and a mix of qualitative and quantitative
reasoning to effectively aid experts in this challenging task.