Semi-formal Definition Research Articles

The Causal Homology Concept

I propose a new account of homology, according to which homology is a correspondence of developmental mechanisms due to common ancestry, formally defined as an isomorphism of causal graphs over lineages. The semiformal definition highlights the role of homology as a higher-order principle unifying evolutionary models and also provides definite meanings to concepts like constraints, evolvability, and novelty. The novel interpretation of homology suggests a broad perspective that accommodates evolutionary developmental biology and traditional population genetics as distinct but complementary approaches to understand evolution, prompting further empirical and theoretical research.

Logics of Common Ground

According to Clark's seminal work on common ground and grounding, participants collaborating in a joint activity rely on their shared information, known as common ground, to perform that activity successfully, and continually align and augment this information during their collaboration. Similarly, teams of human and artificial agents require common ground to successfully participate in joint activities. Indeed, without appropriate information being shared, using agent autonomy to reduce the workload on humans may actually increase workload as the humans seek to understand why the agents are behaving as they are. While many researchers have identified the importance of common ground in artificial intelligence, there is no precise definition of common ground on which to build the foundational aspects of multi-agent collaboration. In this paper, building on previously-defined modal logics of belief, we present logic definitions for four different types of common ground. We define modal logics for three existing notions of common ground and introduce a new notion of common ground, called salient common ground. Salient common ground captures the common ground of a group participating in an activity and is based on the common ground that arises from that activity as well as on the common ground they shared prior to the activity. We show that the four definitions share some properties, and our analysis suggests possible refinements of the existing informal and semi-formal definitions.

On Formalization of the Concept of Value Proposition

This paper presents an original description and a semi-formal definition of the concept of a value proposition, which has been so far used in service science rather intuitively. Our approach is based on utility functions and conceptual modelling techniques. The proposed semi-formalization can be exploited to describe services from the point of view of their (potential) utility for their clients. This description can be used especially to organize a service portfolio in an enterprise in a better way, aid in computer-assisted service composition/decomposition, and provide additional criteria for indexing services in a service brokering task. In order to be able to describe a value proposition more accurately, we present a semi-formal definition of the concept of a service system. We perceive a value proposition as the main input taken into account by a future service client when evaluating whether or not to become the client of the service proposed by a service provider. A value proposition itself is modelled as a collection of values which indicate the extent of “how much” a given service behaves according to a given set of service characteristics. The presented approach is illustrated on the example of a concrete service. [Service Science, ISSN 2164-3962 (print), ISSN 2164-3970 (online), was published by Services Science Global (SSG) from 2009 to 2011 as issues under ISBN 978-1-4276-2090-3.]

A precise definition of basic relational notions and of the relational algebra

This paper presents a precise definition of basic relational notions as well as a precise and general definition of the relational algebra. The paper also illustrates a method for developing semi-formal definitions of data models. A nearly formal definition of relations with unordered attributes is given, and algebraic operations are described as operating on and producing relations thus defined. The definition of algebric operations contains, as a special case, the "classical" definition of the algebra (see e.g. [CODD72]). But, in addition, several operations are generalized. The closure of the algebra is characterized precisely, with the help of an operation for renaming relation attributes.