What's the point?
I am having a hard time here. I get triples. I get that I want to work with a collection of triples. But what are the main, important differences between a Model, DataSource, Dataset, Graph, and DataSetGraph? What are their lifecycles? Which are designed to be kept alive for a long time, and which should be transient? What triples get persisted, and when? What stays in memory? And how are triples shared (if at all) across these five things? I'll take an RTFM answer, if there's a simple summary that... [More]
Jena Schema Generator
There is a useful script that comes bundled with Jena.
On Windows, this is
On Linux this is
The Schema Generator can be used to generate a Java class file with all the Ontology classes and properies defined within the Ontology model. A complete HOWTO can be found on the Jena site .
Usage is simple:
schemagen -i MyOntology.owl -o MyJavaFile.java
All the Ontology Class types are defined as Jena Resource object instances, and all the Ontology Predicate... [More]
We don't know whether the information we find on the Web is accurate or not . The Dublin Core model describes a resource for the purpose of discovery. The W3C PROV model describes entities and processes involved in producing and delivering that resource. This article introduces the mapping between both models.
Rationale for Mapping DC Terms to PROV:
This mapping gives insight into the different characteristics of both data models (in particular it explains PROV from a Dublin Core point of view).
This mapping can be used to extract... [More]
The Mechanics and Value of an Ontology Model
An Ontology is a "specification of a conceptualization" ( Tom Gruber ). I still don’t understand what this means. This is a difficult definition, and has done little to further the understanding of Ontologies, and how they can help in the enterprise. A far better definition of an Ontology is “a description of things that exist and how they relate to each other” ( Chris Welty ). Ontologies and Natural Language Processing (NLP) can often be seen as two sides of the same coin.
Spatial Relations through Prepositions
What is a preposition?
Prepositions are function words and characteristically express spatial relations. Like any function word, prepositions are important for the structure they bring to a sentence.
A function word has little semantic content of its own and chiefly indicates a grammatical relationship. The extraction of semantics (that is, meaning) from English text is chiefly served by examination of content words. Function words serve an important role in determining the structure of the... [More]
Linking verbs are about characteristics. Linking verbs do not express actions. Instead, they connect the subject of the verb to additional information about the subject.
In contrast to intranstives , linking verbs cannot end sentences, nor can they be followed immediately by adverbs. These must be followed by either nouns or adjectives, one or the other; those nouns and adjectives may be single words or multiple-word phrases. In addition, linking verbs constitute a small class of probably no more than a few dozen... [More]
Two-Place Transitive Verbs (VC)
The second two-place transitive verb construction is similar in that the action of the verb is divided equally in two places. Constructions with VC verbs are often more subjective in nature. The ability to express the context of the action (through reification) is a must in this case.
Given the business scenarios expressed in the VG section, the loss of one of the triples would have meant the loss of important context. But it would not have impacted the objective truth of what remained.
Triple Extraction from Verbs
Verbs are basic to sentences. Verbs determine the other constituents (of the sentence), and define the relationship between these constituents. A verb can tell you that a certain noun phrase functions as a subject, or that another other noun phrase functions as an object, or a predicate noun, or perhaps an object complement.
There are six types of verbs that define core sentences. These verbs are differentiated by two criteria:
The constituent that follows immediately to its right.
The relationship... [More]
Two-Place Transitive Verbs (Vg)
When we looked at transitive verbs, we saw that action was passed to a single object. We might refer to this as a “one-place” transitive verb as in, all the action passes to one place. In a two place transitive verb, we might reasonably infer that the action passes to two places. Vg transitive verbs are followed immediately by two noun phrases. Each of these noun phrases are equal recipients of the action performed by the subject.
The school board NP:Subj gave Vg a raise NP:DObj to the teachers... [More]
The sentence may be a truncated three words or include a lengthy description, but the action never moves beyond the subject. To use the old riddle, there is no one else in the sentence to hear if the lone tree falling in the forest makes a sound.
An intransitive verb can be used to end the sentence.
The mayor spoke .
The president resigned .
The dog barked .
Intransitive verbs may be followed by an adverb (something that adds to a verb):
The mayor spoke convincingly .
A transitive verb demonstrates an action that passes from one entity to another. We might say that the first entity (the subject) commits the action on the second entity (the object). The action is what links the subject to the object.
This connection between a subject and an object is considered a triple. The action passes over from the subject to the object. Transitive verbs lend themselves well to triple extraction from unstructured text.
The performer of the action is not always the subject of the verb.... [More]
Reification generally refers to making something real, bringing it into being, or making something concrete. Or, the making of something abstract into something more concrete or real; the action of regarding or treating an idea, concept, etc., as if having material existence. This definition is about as useful as the classic definition for an Ontology. I don't think the word reflects the idea. But who cares. It's a simple and powerful concept in RDF, and easy to understand . So let’s say we log onto Wikipedia or some other trusted... [More]