“Those found responsible have been sacked”: some observations on the usefulness of error

Erik Hollnagel’s body of work in the past three decades has molded much of the current research approach to system safety, particularly notions of “error”. Hollnagel regards “error” as a dead-end and avoids using the term. This position is consistent with Rasmussen’s claim that there is no scientifically stable category of human performance that can be described as “error”. While this systems view is undoubtedly correct, “error” persists. Organizations, especially formal business, political, and regulatory structures, use “error” as if it were a stable category of human performance. They apply the term to performances associated with undesired outcomes, tabulate occurrences of “error”, and justify control and sanctions through “error”. Although a compelling argument can be made for Hollnagel’s view, it is clear that notions of “error” are socially and organizationally productive. The persistence of “error” in management and regulatory circles reflects its value as a means for social control.     

Process mining: a two-step approach to balance between underfitting and overfitting

Process mining includes the automated discovery of processes from event logs. Based on observed events (e.g., activities being executed or messages being exchanged) a process model is constructed. One of the essential problems in process mining is that one cannot assume to have seen all possible behavior. At best, one has seen a representative subset. Therefore, classical synthesis techniques are not suitable as they aim at finding a model that is able to exactly reproduce the log. Existing process mining techniques try to avoid such “overfitting” by generalizing the model to allow for more behavior. This generalization is often driven by the representation language and very crude assumptions about completeness. As a result, parts of the model are “overfitting” (allow only for what has actually been observed) while other parts may be “underfitting” (allow for much more behavior without strong support for it). None of the existing techniques enables the user to control the balance between “overfitting” and “underfitting”. To address this, we propose a two-step approach. First, using a configurable approach, a transition system is constructed. Then, using the “theory of regions”, the model is synthesized. The approach has been implemented in the context of ProM and overcomes many of the limitations of traditional approaches.     

Artificial life based on the programmed self-decomposition model, SIVA

To examine the effect and significance of the phenomenon of death, we have developed an artificial life simulator, SIVA-III (simulator for individuals of virtual automata III), based on a “programmed self-decomposition model”. The architecture of this simulator consists of a “finite heterogeneous habitation environment” and “artificial life with programmed individual death and concurrent self-decomposition”. We conducted experiments under various settings to comparare and contrast mortal life and immortal life. The results clearly demonstrated the validity of a self-decomposing, programmed individual death, and the limitations inherent in immortal life, suggesting a striking superiority of mortal life over immortal life. This work was presented in part at the Fifth International Symposium on Artificial Life and Robotics, Oita, Japan, January 26–28, 2000     

Crypt-equivalent algebraic specifications

Summary Equivalence is a fundamental notion for the semantic analysis of algebraic specifications. In this paper the notion of “crypt-equivalence” is introduced and studied w.r.t. two “loose” approaches to the semantics of an algebraic specificationT: the class of all first-order models ofT and the class of all term-generated models ofT. Two specifications are called crypt-equivalent if for one specification there exists a predicate logic formula which implicitly defines an expansion (by new functions) of every model of that specification in such a way that the expansion (after forgetting unnecessary functions) is homologous to a model of the other specification, and if vice versa there exists another predicate logic formula with the same properties for the other specification. We speak of “first-order crypt-equivalence” if this holds for all first-order models, and of “inductive crypt-equivalence” if this holds for all term-generated models. Characterizations and structural properties of these notions are studied. In particular, it is shown that firstorder crypt-equivalence is equivalent to the existence of explicit definitions and that in case of “positive definability” two first-order crypt-equivalent specifications admit the same categories of models and homomorphisms. Similarly, two specifications which are inductively crypt-equivalent via sufficiently complete implicit definitions determine the same associated categories. Moreover, crypt-equivalence is compared with other notions of equivalence for algebraic specifications: in particular, it is shown that first-order cryptequivalence is strictly coarser than “abstract semantic equivalence” and that inductive crypt-equivalence is strictly finer than “inductive simulation equivalence” and “implementation equivalence”.     

System design of “Ba”-like stages for improvisational acts via Leibnizian space–time and Peirce’s existential graph concepts

A framework for “improvisational” social acts and communication is introduced by referring to the idea of “relationalism” such as natural farming, permaculture and deep ecology. Based on this conception, the notion of Existential Graph by C. S. Peirce is introduced. The notion of extended self in deep ecology is substantiated based on the Roy Adaptation Model in Nursing Theory and Narrative approaches. By focusing on Leibnizian notions of space and time and by introducing Petri net, a spatio-temporal model of improvisation is constructed. This model is expected to substantiate the interesting notion of “Ba” proposed by H. Shimizu reflecting Japanese culture.     

Distributed agreement in tile self-assembly

Laboratory investigations have shown that a formal theory of fault-tolerance will be essential to harness nanoscale self-assembly as a medium of computation. Several researchers have voiced an intuition that self-assembly phenomena are related to the field of distributed computing. This paper formalizes some of that intuition. We construct tile assembly systems that are able to simulate the solution of the wait-free consensus problem in some distributed systems. (For potential future work, this may allow binding errors in tile assembly to be analyzed, and managed, with positive results in distributed computing, as a “blockage” in our tile assembly model is analogous to a crash failure in a distributed computing model.) We also define a strengthening of the “traditional” consensus problem, to make explicit an expectation about consensus algorithms that is often implicit in distributed computing literature. We show that solution of this strengthened consensus problem can be simulated by a two-dimensional tile assembly model only for two processes, whereas a three-dimensional tile assembly model can simulate its solution in a distributed system with any number of processes.     

Formalizing coexistential communication as co-creation of Leibnizian spatio-temporal fields

This paper proposes deep and fundamental structures of communication among persons in a “coexistential” setting. The basic framework for this formalization of communication structures is Leibnizian notions of space and time together with the notion of the Existential Graph by C. S. Peirce and that of the Petri net, more precisely, the occurrence net. The fundamental structures of coexistential communication are then formalized as co-creation of Leibnizian space and time in such a manner that they are used to link the communicated messages, thus establishing the “coexistential atmosphere and field” (“Ba” in Japanese) among the individuals. This framework is then applied to the analysis of theater play communication. Finally, the framework of information edaphology is also introduced to discuss the growth processes of individuals and communities through coexistential communication.     

Rudolph M. Schindler—Space Reference Frame,Modular Coordination and the “Row”

While Rudolph Schindler’s “space reference frame” is becoming better known, its relationship to the “row” has only been recently investigated. The theory of the “row” counters traditional proportional notions, many of which are derived from the principle of geometric similitude a principle which is mostly represented in architectural drawings by regulating lines and triangulation.