350 research outputs found
PriCL: Creating a Precedent A Framework for Reasoning about Privacy Case Law
We introduce PriCL: the first framework for expressing and automatically
reasoning about privacy case law by means of precedent. PriCL is parametric in
an underlying logic for expressing world properties, and provides support for
court decisions, their justification, the circumstances in which the
justification applies as well as court hierarchies. Moreover, the framework
offers a tight connection between privacy case law and the notion of norms that
underlies existing rule-based privacy research. In terms of automation, we
identify the major reasoning tasks for privacy cases such as deducing legal
permissions or extracting norms. For solving these tasks, we provide generic
algorithms that have particularly efficient realizations within an expressive
underlying logic. Finally, we derive a definition of deducibility based on
legal concepts and subsequently propose an equivalent characterization in terms
of logic satisfiability.Comment: Extended versio
Combinatorial Games with a Pass: A dynamical systems approach
By treating combinatorial games as dynamical systems, we are able to address
a longstanding open question in combinatorial game theory, namely, how the
introduction of a "pass" move into a game affects its behavior. We consider two
well known combinatorial games, 3-pile Nim and 3-row Chomp. In the case of Nim,
we observe that the introduction of the pass dramatically alters the game's
underlying structure, rendering it considerably more complex, while for Chomp,
the pass move is found to have relatively minimal impact. We show how these
results can be understood by recasting these games as dynamical systems
describable by dynamical recursion relations. From these recursion relations we
are able to identify underlying structural connections between these "games
with passes" and a recently introduced class of "generic (perturbed) games."
This connection, together with a (non-rigorous) numerical stability analysis,
allows one to understand and predict the effect of a pass on a game.Comment: 39 pages, 13 figures, published versio
A Logical Method for Policy Enforcement over Evolving Audit Logs
We present an iterative algorithm for enforcing policies represented in a
first-order logic, which can, in particular, express all transmission-related
clauses in the HIPAA Privacy Rule. The logic has three features that raise
challenges for enforcement --- uninterpreted predicates (used to model
subjective concepts in privacy policies), real-time temporal properties, and
quantification over infinite domains (such as the set of messages containing
personal information). The algorithm operates over audit logs that are
inherently incomplete and evolve over time. In each iteration, the algorithm
provably checks as much of the policy as possible over the current log and
outputs a residual policy that can only be checked when the log is extended
with additional information. We prove correctness and termination properties of
the algorithm. While these results are developed in a general form, accounting
for many different sources of incompleteness in audit logs, we also prove that
for the special case of logs that maintain a complete record of all relevant
actions, the algorithm effectively enforces all safety and co-safety
properties. The algorithm can significantly help automate enforcement of
policies derived from the HIPAA Privacy Rule.Comment: Carnegie Mellon University CyLab Technical Report. 51 page
From truth to computability I
The recently initiated approach called computability logic is a formal theory
of interactive computation. See a comprehensive online source on the subject at
http://www.cis.upenn.edu/~giorgi/cl.html . The present paper contains a
soundness and completeness proof for the deductive system CL3 which axiomatizes
the most basic first-order fragment of computability logic called the
finite-depth, elementary-base fragment. Among the potential application areas
for this result are the theory of interactive computation, constructive applied
theories, knowledgebase systems, systems for resource-bound planning and
action. This paper is self-contained as it reintroduces all relevant
definitions as well as main motivations.Comment: To appear in Theoretical Computer Scienc
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