5th SIEP Workshop

The 5th SIEP Workshop takes place at the KU Leuven from 21 to 22 March 2016.

Program

For the talks marked with (*) you can find an abstract below.

Monday, 21 March

10:00-10:45
Pieter Van Hertum: Distributed Autoepistemic Logic and its Application to Access Control (*)

10:45-11:00
Coffee break

11:00-12:00
Diego Agustín Ambrossio and Marcos Cramer: A Non-Monotonic Logic for Distributed Access Control (*)

12:00-14:00
Lunch break

14:00-15:30
Marcos Cramer: AGM revocation (talk and discussion)

15:30-16:00
Coffee break

16:00-17:00
Closed meeting with Marc Denecker, Leon van der Torre, Pieter Van Hertum and Marcos Cramer: Organizational aspects of the SIEP project

Tuesday, 22 March

10:00-10:45
Pieter Van Hertum: A Possible-world Semantics for a multi-agent modal logic accomodating Only Knowing and Common Knowledge

10:45-11:00
Coffee break

11:00-12:00
Everyone: Discussion about the semantics proposed in Pieter's talk

12:00-13:30
Lunch break

13:30-15:00
Marcos Cramer and Zohreh Baniasadi: The KR paradigm applied to delegation and revocation

Abstracts

Pieter Van Hertum: Distributed Autoepistemic Logic and its Application to Access Control

We define and study an extension of autoepistemic logic (AEL) called distributed autoepistemic logic (dAEL) with multiple agents that have full introspection in their own knowledge as well as in that of others. This mutual full introspection between agents is motivated by an application of dAEL in access control. We define 2- and 3-valued semantic operators for dAEL. Using these operators, approximation fixpoint theory, an abstract algebraic framework that unifies different knowledge representation formalisms, immediately yields us a family of semantics for dAEL, each based on different intuitions that are well-studied in the context of AEL. We define a mapping from dAEL to AEL and prove that the semantics that we have defined for dAEL match the corresponding semantics for AEL under this mapping. The application in access control also motivates an extension of dAEL with inductive definitions (dAEL(ID)). We explain a use-case from access control to demonstrate how dAEL(ID) can be fruitfully applied to this domain and discuss how well-suited the different semantics are for the application in access control.

Marcos Cramer and Diego Agustín Ambrossio: A Non-Monotonic Logic for Distributed Access Control

We define Distributed Access Control Logic (DACL), whose main difference from state-of-the-art says-based access control logics is that it is non-monotonic, thus allowing access denials to be modelled straightforwardly in the formalism. Additionally DACL allows for access rights and other properties relevant to access control to be defined inductively, which increases its expressive power compared to other first-order access control logics. The semantics of DACL is based on the well-founded semantics for autoepistemic logic. By considering some application scenarios, we compare DACL with other says-based access control logics as well as with other semantics of autoepistemic logic. Furthermore, we define a query-driven decision procedure for the propositional fragment of DACL, which allows to determine access rights while minimizing the information flow between principals in order to reduce privacy concerns.