5,597 research outputs found
Guidelines for empirical evaluations of conceptual modeling grammars
Conceptual modeling grammars are used to create scripts that represent someone's perception, or some group's negotiated perception, of domain semantics. For many years, researchers have evaluated conceptual modeling grammars to determine ways that they can be improved. One way to evaluate them is to empirically evaluate the strengths and weaknesses of the grammars in terms of their effectiveness and efficiency in generating scripts. A number of researchers have proposed guidelines for the design of empirical research to conduct such evaluations. Although these guidelines have proved useful, further clarification is needed in relation to (1) criteria for evaluating grammar performance, (2) characteristics of grammars that can influence grammar performance, and (3) factors that must be considered when testing the effect of grammar characteristics on grammar performance. We review past conceptual modeling research and provide guidelines for addressing these three issues. We also illustrate how the guidelines would apply to studies that evaluate conceptual modeling grammars from an ontological perspective. Finally, we discuss how the guidelines extend those offered in past research and the implications of our work for future research
Strong and Weak Optimizations in Classical and Quantum Models of Stochastic Processes
Among the predictive hidden Markov models that describe a given stochastic
process, the {\epsilon}-machine is strongly minimal in that it minimizes every
R\'enyi-based memory measure. Quantum models can be smaller still. In contrast
with the {\epsilon}-machine's unique role in the classical setting, however,
among the class of processes described by pure-state hidden quantum Markov
models, there are those for which there does not exist any strongly minimal
model. Quantum memory optimization then depends on which memory measure best
matches a given problem circumstance.Comment: 14 pages, 14 figures;
http://csc.ucdavis.edu/~cmg/compmech/pubs/uemum.ht
Prediction, Retrodiction, and The Amount of Information Stored in the Present
We introduce an ambidextrous view of stochastic dynamical systems, comparing
their forward-time and reverse-time representations and then integrating them
into a single time-symmetric representation. The perspective is useful
theoretically, computationally, and conceptually. Mathematically, we prove that
the excess entropy--a familiar measure of organization in complex systems--is
the mutual information not only between the past and future, but also between
the predictive and retrodictive causal states. Practically, we exploit the
connection between prediction and retrodiction to directly calculate the excess
entropy. Conceptually, these lead one to discover new system invariants for
stochastic dynamical systems: crypticity (information accessibility) and causal
irreversibility. Ultimately, we introduce a time-symmetric representation that
unifies all these quantities, compressing the two directional representations
into one. The resulting compression offers a new conception of the amount of
information stored in the present.Comment: 17 pages, 7 figures, 1 table;
http://users.cse.ucdavis.edu/~cmg/compmech/pubs/pratisp.ht
Users’ Continued Usage of Online Healthcare Virtual Communities: An Empirical Investigation in the Context of HIV Support Communities
This study uses data from an online HIV/AIDS health support virtual community to examine whether users’ emotional states and the social support they receive influence their continued usage. We adopt grief theory to conceptualize the negative emotions that people living with HIV/AIDS could experience. Linguistic analysis is used to measure the emotional states of the users and the informational and emotional support that they receive. Results show that users showing a higher level of disbelief and yearning are more likely to leave the community while those with a high level of anger and depression are more likely to stay on. Users who receive more informational support are more likely to leave once they have obtained the information they sought, but those who receive more emotional support are more likely to stay on. The findings of this study can help us better understand users’ support seeking behavior in online support VCs
The solution of the Sixth Hilbert Problem: the Ultimate Galilean Revolution
I argue for a full mathematisation of the physical theory, including its
axioms, which must contain no physical primitives. In provocative words:
"physics from no physics". Although this may seem an oxymoron, it is the royal
road to keep complete logical coherence, hence falsifiability of the theory.
For such a purely mathematical theory the physical connotation must pertain
only the interpretation of the mathematics, ranging from the axioms to the
final theorems. On the contrary, the postulates of the two current major
physical theories either don't have physical interpretation (as for von
Neumann's axioms for quantum theory), or contain physical primitives as
"clock", "rigid rod ", "force", "inertial mass" (as for special relativity and
mechanics). A purely mathematical theory as proposed here, though with limited
(but relentlessly growing) domain of applicability, will have the eternal
validity of mathematical truth. It will be a theory on which natural sciences
can firmly rely. Such kind of theory is what I consider to be the solution of
the Sixth Hilbert's Problem. I argue that a prototype example of such a
mathematical theory is provided by the novel algorithmic paradigm for physics,
as in the recent information-theoretical derivation of quantum theory and free
quantum field theory.Comment: Opinion paper. Special issue of Philosophical Transaction A, devoted
to the VI Hilbert problem, after the Workshop "Hilbert's Sixth Problem",
University of Leicester, May 02-04 201
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