36 research outputs found
Facticity as the amount of self-descriptive information in a data set
Using the theory of Kolmogorov complexity the notion of facticity {\phi}(x)
of a string is defined as the amount of self-descriptive information it
contains. It is proved that (under reasonable assumptions: the existence of an
empty machine and the availability of a faithful index) facticity is definite,
i.e. random strings have facticity 0 and for compressible strings 0 < {\phi}(x)
< 1/2 |x| + O(1). Consequently facticity measures the tension in a data set
between structural and ad-hoc information objectively. For binary strings there
is a so-called facticity threshold that is dependent on their entropy. Strings
with facticty above this threshold have no optimal stochastic model and are
essentially computational. The shape of the facticty versus entropy plot
coincides with the well-known sawtooth curves observed in complex systems. The
notion of factic processes is discussed. This approach overcomes problems with
earlier proposals to use two-part code to define the meaningfulness or
usefulness of a data set.Comment: 10 pages, 2 figure
Overview of BioCreative II gene mention recognition.
Nineteen teams presented results for the Gene Mention Task at the BioCreative II Workshop. In this task participants designed systems to identify substrings in sentences corresponding to gene name mentions. A variety of different methods were used and the results varied with a highest achieved F1 score of 0.8721. Here we present brief descriptions of all the methods used and a statistical analysis of the results. We also demonstrate that, by combining the results from all submissions, an F score of 0.9066 is feasible, and furthermore that the best result makes use of the lowest scoring submissions
Structuring and extracting knowledge for the support of hypothesis generation in molecular biology
Background: Hypothesis generation in molecular and cellular biology is an empirical process in which knowledge derived from prior experiments is distilled into a comprehensible model. The requirement of automated support is exemplified by the difficulty of considering all relevant facts that are contained in the millions of documents available from PubMed. Semantic Web provides tools for sharing prior knowledge, while information retrieval and information extraction techniques enable its extraction from literature. Their combination makes prior knowledge available for computational analysis and inference. While some tools provide complete solutions that limit the control over the modeling and extraction processes, we seek a methodology that supports control by the experimenter over these critical processes. Results: We describe progress towards automated support for the generation of biomolecular hypotheses. Semantic Web technologies are used to structure and store knowledge, while a workflow extracts knowledge from text. We designed minimal proto-ontologies in OWL for capturing different aspects of a text mining experiment: the biological hypothesis, text and documents, text mining, and workflow provenance. The models fit a methodology that allows focus on the requirements of a single experiment while supporting reuse and posterior analysis of extracted knowledge from multiple experiments. Our workflow is composed of services from the 'Adaptive Information Disclosure Application' (AIDA) toolkit as well as a few others. The output is a semantic model with putative biological relations, with each relation linked to the corresponding evidence. Conclusion: We demonstrated a 'do-it-yourself' approach for structuring and extracting knowledge in the context of experimental research on biomolecular mechanisms. The methodology can be used to bootstrap the construction of semantically rich biological models using the results of knowledge extraction processes. Models specific to particular experiments can be constructed that, in turn, link with other semantic models, creating a web of knowledge that spans experiments. Mapping mechanisms can link to other knowledge resources such as OBO ontologies or SKOS vocabularies. AIDA Web Services can be used to design personalized knowledge extraction procedures. In our example experiment, we found three proteins (NF-Kappa B, p21, and Bax) potentially playing a role in the interplay between nutrients and epigenetic gene regulation
Industrial requirements for ML application technology
this paper, it is clear that we have only a very rudimentary idea of a methodology for ML. On might ask why the ML community has made so little progress in comparison to e.g. the database community. There ara standard methods for the design and implementation of a database. Such things are not yet realised for ML. The main reason may be that a methodology for ML is much harder because there are fundamental philosophical issues on a more abstract level that have not been solved. A general theory of scientific heuristics, that would be a basis for such a methodology is missing. Many issues concerning a methodology for ML are really basic issues in methodology of science in disguise. My general feeling is that it will be difficult to formulate a methodology for ML is the underlying general patterns of scientic heuristics and creativity are not well understood. Recent work in complexity theory, and methodology of science may help us here
The Power and Perils of MDL
We point out a potential weakness in the application of the celebrated Minimum Description Length (MDL) principle for model selection. Specifically, it is shown that (although the index of the model class which actually minimizes a two-part code has many desirable properties) a model which has a shorter twopart code-length than another is not necessarily better (unless of course it achieves the global minimum). This is illustrated by an application to infer a grammar (DFA) from positive examples. We also analyze computability issues, and robustness under recoding of the data. Generally, the classical approach is inadequate to express the goodness-of-fit of individual models for individual data sets. In practice however, this is precisely what we are interested in: both to express the goodness of a procedure and where and how it can fail. To achieve this practical goal, we paradoxically have to use the, supposedly impractical, vehicle of Kolmogorov complexity
Finding Constraints for Semantic Relations via Clustering
Automatic recognition of semantic relations constitutes an important part of information
extraction. Many existing information extraction systems rely on syntactic information
found in a sentence to accomplish this task. In this paper, we look into relation arguments
and claim that some semantic relations can be described by constraints imposed on them.
This information would provide more insight on the nature of semantic relations and could
be further combined with the evidence found in a sentence to arrive at actual extractions