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Orientation to Methods
SOCoP 2012 Workshop Gary Berg-Cross
SOCoP Executive Secretary
Nov. 29-30, 2012
U. S. Geological Survey National Center 12201 Sunrise Valley Dr., Reston VA
Orientation to Semantic Methods for Workshop 2
Outline
1. Intro to ODPs2. Ontology Engineering
1. Problems, Component and Relation Identification & Clarification
2. Conceptualization Phase Systematic
organization & framing with visual expression
3. Formalization
GeometryA point is the most fundamental object in geometry. A point represents position only; it has zero size
Geometry In NeoGeo OntologySuper-class grouping all geometrical representations (includes non-RDF formats e.g. KML, GML, WKT..)URI http://geovocab.org/geometry#Geometry
Orientation to Semantic Methods for Workshop 3
Examples of CPs
From PhD Course on Computational Ontologies @ University of Bologna 2011 Author(s): Valentina Presutti, Aldo Gangemi, Eva Blomqvist;
http://stlab.istc.cnr.it/documents/slides/PhDCourse/Bologna2011/ExtremeDesign.pdf
Colon
Orientation to Semantic Methods for Workshop 4
Conceptual Pattern- A Schema for Motion:
S
G
onPath
We can generally outline what we mean by Motion in a vocabulary of lexical terms to represent concepts (Start of a Path) typically used in this particular domain.
All paths have a start point
End point could be represented in
a coordinate system
We remain general in the pattern since this is a cognitive activity & the concept has flexible semantics depending on human intentions and perspectives. The pattern can generate alternate descriptions conforming to alternate interpretations.
Orientation to Semantic Methods for Workshop 5
Path-name
-start object -end object
-path description-medium - surface
is part ofMotion
has part
hasPath
MovingObject
hasPath
Geo-VoCamp Patterns – Path from an infoperspective
Just OWL ClassesMotion is an OWL:Class
Light constraints by relationsand what is related
Orientation to Semantic Methods for Workshop 6
Point of Interest (POI) Pattern:Geographic information constructs, not direct representations of real entities
Some placeholdersIdeas for later analysis.
Groundable by adding data not more semantics
Orientation to Semantic Methods for Workshop 7
Composing New ODP from Old: Semantic Trajectory
•Preserves axioms from other ODPs•Adds concepts Data for Model:mikestrip a :SemanticTrajectory; :hasSegment [a :Segment; :from :fix1; // mikeshome:to :fix2;// rest stop :traversedBy :fordFocus], [a :Segment; :from :fix1; // rest stop :to :fix2],// WrightStateU :traversedBy :fordFocus], [a :Segment;:from :fix1; // WrightStateUniversity:to:fix2],//..:fixn].:mike a foaf:Person:mikesFordFocus a motion:MovingObject.:garminEtrexVistaC a:Source.geo:Geometry rdfs:subClassOf :Position.:mikesFordFocus a motion:MovingObject]:motion1 a……
Orientation to Semantic Methods for Workshop 8
Step 1:Acquire Scoped Domain Knowledge & Vocabulary Principle: Clarify & Indentify Problem, Components & Relations
Identify scope: We prefer working from scenario examples with potential data to help structure requirements, defining the purpose of the ontology and illustrate the nature of a problem topic.
What are we talking about? What do you mean when you use these words.. Streams as objects (not processes?)…..
What is the scope? Not how streams flood, or pools of water,… What is the purpose of this modeling? What data is relevant….
We should leverage existing work but not slavishly leverage thoughts & experiences from other groups that are collaborating on
ontologies reference or include supporting vocabularies/ontologies,
Terminologies can be a starting point, but the path should be to the concepts behind what the terms mean to domain people and be relatable to “data.”
Controlled vocabularies and other terminologies are necessary lexical resources to refer to concepts
Linguistics or conceptual analysis Handle multiple meaning and similarities
Orientation to Semantic Methods for Workshop 9
Understanding from Definitions & Analysis Starts on partitioning experience into important/general parts & relations Example of semantics from definitions of a noun phrase “stream reach” –
what we are talking about?: a continuous part of a physical object stream (in a network) between
two specified points. Reaches are commonly defined by a length of stream between two
confluences, or a lake or pond. Addition - Stream - physical container hosting a void in which water can
be stored and through which it can flow.
Part of
Natural Aggregation into Systems
Platt?
Orientation to Semantic Methods for Workshop 10
Some Design Detail on the Problem Space/System of Stream Reach
ReachPointR 101
ReachPoint R 102
Similar/uniform CharacteristicsstreamReach hasProperty, uniform
Flow to downstreamend
Reaches in a stream network are segments of surface water with similar hydrologic characteristics.Each reach is assigned a unique reach number and a flow direction. (attributes)The length of the reach, the type of reach, and differing important information are assigned as attributes to each reach depending on perspective.
Ecologists and hydrologists will employ different concepts.
Void ofwater
Monitoring
Orientation to Semantic Methods for Workshop 11
Stream Reach by the Book – not everyday use“Reach” means a watercourse that has a continuous channel bed that meets one of the
following requirements: (a) the channel bed is at least 100 m in length, measured from any of the following locations
to the next of any of the following locations: (i) the location where the watercourse begins or ceases to have a continuous channel bed; (ii) the location where
(A) a significant change in morphology occurs, for example at the junction of a major tributary, and (B) the mean width of the channel bed, as measured over a representative 100 m length of channel bed, upstream and downstream of the morphological change is sufficient to change the riparian class of the watercourse, if the watercourse were a stream;
(iii) the location where (A) a significant change in morphology occurs, eg at the junction of a major tributary, and (B) the mean gradient of the channel bed, as measured over a representative 100 m length of
channel bed upstream and downstream the morphological change, changes from less than 20% to 20% or more, or vice versa;
(b) the channel bed is at least 100 m in length, made up of one or more segments, the boundaries of which are any of the locations referred to in paragraph (a); (c) the channel bed is less than 100 m in length, if the continuous channel bed
(i) is known to contain fish, (ii) flows directly into a fish stream or a lake that is known to contain fish, or (iii) flows directly into a domestic water intake.
See National Hydrography Dataset http://nhd.usgs.gov/ & http://nhd.usgs.gov/nhd_faq.html#q105
Orientation to Semantic Methods for Workshop 12
Conceptualization Qualities
1. Correctly captures intuitions of domain experts as they express intended content (expressivity)
1. These statements should be understandable to humans E.g. Touches” is symmetrical (StramReach-101 touches
StramReach-102 so visa versa..Leg1ofTrip touches Leg2)• Formalization will make them processable by computing
systems.
2. Minimally redundant - no unintended synonyms
3. Multiple possible meanings of concepts are reduced so that systems & people can recognize commonalities and differences in the semantics of the concepts that they use.
Orientation to Semantic Methods for Workshop 13
Forge Consensus on Some of the Relevant Terms/ Concepts & Express
To be a quality model (& later ontology) we should be able to
make meaningful statements about what exists in our focused domain/topic and
establish consensus about the meaning of terms (in general) Stream reach/segment is part of a stream Streams and their parts are watercourses Watercourses are containers Watercourses may contain water Stream segment/reaches have stream
direction Steams have constituents Constituents had Some stream reach constituents are uniform
in character…..
Inside
Outside
Boundary
The water is in the stream.The water is surface water.The stream contains a water surface
SpatialRegion
SpatialObject
Aha!A pattern..
Container
Controlled vocabulary suitable for OWL or CL helps
ContainedObject
Orientation to Semantic Methods for Workshop 14
Conceptual Modeling & Design PhaseFrames, Organizes, Structures, Visualizes
Container Pattern Container IsA DUL:SocialObject Container Contains Containee Container hasLocation SpatialLocation Place IsA SpatialLocation Place denotesLocation Container
Axiom: Some ContainedObjects are DUL:PhysicalObjects Axiom: Container contains 0-N contained objects……
Spatial Location Pattern??Region IsA SpatialLocation
SpatialLocation IsA Spatial Region
Simple CM
Language
Orientation to Semantic Methods for Workshop 15
Conceptual Modeling Activities
Design the overall conceptual structure of the domain. This involves objects and their properties consistent with your purpose. Focus on the Parts needed to build a Conceptual Models as a product
for input to Ontology1. Identifying & defining the domain's principal concrete concepts &
building a concept base (Objects ->Classes) 2. Identifying the relationships among the concepts
1. Arrange in taxonomical class hierarchy(s)2. Clarify IsA hierarchies and part-whole relations3. Link concepts via other Relations…..
3. Discuss constraints that characterize key concepts and their relations
1. A Container may contain 0-n objects (empty container idea)2. FlowsInto relation is transitive
Add concepts & relations & individuals to the level of detail necessary to satisfy your purposes. All these will provide commitments to be expressed in an ontological language
Orientation to Semantic Methods for Workshop 16
Class Hierarchies, Attributes & Relations (Path Ontology Examples)
1. Arranging objects as class hierarchies (supporting transitivity)It depends on what vocabulary you adopt:1. Path is a Feature, feature is a spatialThing, spatialThing is a Thing….OR2. Path is a spatialFeature, spatialFeature is a PhysicalObject, (DOLCE) OR3. Path is a Feature, Feature is a SpatialObject, SpatialObject is either a
Feature or a Geometry (GeoSPARQL model) See http://www.opengis.net/ont/OGC-GeoSPARQL/1.0/Feature
2. Attributes (class slots)Path has a startObject, Path has a Name, Path has a Description (“turn onto VA route 247”), some Descriptions are PathGeometries,Sunrise Valley Dr. hasQuantity Length DataPropertyAssertion(.21 :hasValue : " "^^xsd:integer, hasUnit: miles ) ….
3. Relations (Properties) includes such ideas as Contains & hasPartPath 101 hasPart Path101a, Path101a connectedTo Path101b…..
Orientation to Semantic Methods for Workshop 17
Am I Doing Structural, Ontological or Conceptual Analysis & Design ?
There are distinctions, but … each can provide something from its best practices that helps
systematize the information.
Leveraging a Good Conceptual model the formal ontology should represent:
Meanings & Agreed upon Common Understanding Organization
Taxonomy etc. Basic Vocabulary as agreed upon Some instantible connection to the “real world” and data from it.
After Chris Welty’s: Ontology-Driven Conceptual Modeling http://ontolog.cim3.net/file/resource/presentation/OntoClean --ChrisWelty_20041118/OntoClean-2004v1--ChrisWelty_20041118.ppt
Orientation to Semantic Methods for Workshop 18
Option of Aligning Concepts
Each top-level concept in your model might be loosely “aligned” to a top-level concept in a foundational ontology like DUL.
Given an alignment to top-level concepts, you can “define” some the relations between them perhaps by extending the foundational relations that are used in ontologies like DUL to relate their concepts. memberOf and partOf are examples of
foundational relations. We can use them…..
Orientation to Semantic Methods for Workshop 19
Tools
It is often useful to start with hand/board drawings to accommodate conversational flow.
PowerPoint graphics can be used to tidy things up for presentation.
Better yet is a modeling tool like CMAP with support for model constructs and automatic translation into OWL/TTL etc.
Orientation to Semantic Methods for Workshop 20
Formally Committing to our Conceptualization with Axiomatized Semantics
1. Formal –can be represented/put into a form amenable to automated processing [formal language] Ontologies formalize concepts with axioms
defined on such concept vocabularies1. Sufficiently axiomatized – include detailed
constraining descriptions, such as transitivity, as axioms (not just text descriptions)
2. Rigorous – stands up to rational analysis1. Distinguish which concepts have instances
1. Named classes can (potentially) have instances
Orientation to Semantic Methods for Workshop 21
Formalization with Axiomatized Semantics
RDFS is Modestly Formal - Used to Define a Scale with a small concept vocabularies
1. scale:hasPoint (members);
2. rdfs:subPropertyOf scovo:datasetOf ;
3. rdfs:label "has point" ;
4. rdfs:comment "Associates a Scale with the Point(s) of which it is comprised."
5. rdfs:domain scale:Scale ;
6. rdfs:range scale:Point .
From VoCamp with Ordnance Survey
Orientation to Semantic Methods for Workshop 22
Nearness Model- uses Scale Model
4 Point Scale of here, nearest, nearer & close using before & after Properties
The web of logical statements carriesthe meaning.
Orientation to Semantic Methods for Workshop 23
Better Semantics Using OWL Language Transitive, inverse, symmetrical, reflexive/irreflexive
properties Using RDFS we can’t say that: isPartOf is a transitive property (branch isPartOf
River and tributary isPartOf branch), Need Transitive property for Regions to say that the
subRegionOf property between regions is transitive <owl:TransitiveProperty rdf:ID="subRegionOf">
<rdfs:domain rdf:resource="#Region"/> <rdfs:range rdf:resource="#Region"/> </owl:TransitiveProperty>
hasPart is the inverse of isPartOf or A=A is reflexive but part relations are irreflexive
These are things that can be said in OWL (Web Ontology Language)
Orientation to Semantic Methods for Workshop 24
Descriptive Logic
OWL uses a subset of 1st Order Logic called Descriptive Logic (DL) that is decidable and simple enough to represent and describe objects and properties
Has a terminological (T-box) part to create classes some by sub-typing and saying that physical objects are a sub-type of object <flood isa disaster>
Has an assertional (A-box) part to describe relations (other than sub-type) between instances (Reston is_located_in VA) and to use axioms to constrain meaning.
Orientation to Semantic Methods for Workshop 25
Motion / Path RDF/ontology in Turtle (TTL): (Terse RDF Triple Language – uses a . , ;])
Namespace prefixes@prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> . @prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> .@prefix owl: <http://www.w3.org/2002/07/owl#> . @prefix xsd: <http://www.w3.org/2001/XMLSchema#> .@prefix geo: <http://www.opengis.net/def/geosparql/> . @prefix sf: <http://www.opengis.net/def/sf/> .@prefix gml: <http://www.opengis.net/def/gml/> . @prefix dc: <http://purl.org/dc/elements/1.1/> .@prefix spw:
<http://www.w3.org/2001/sw/BestPractices/OEP/SimplePartWhole/part.owl> .
@prefix event: <> . @prefix : <http://vocamp.org/ontology/movement/spatial/> . (Default prefix)
# Ontology description :Ontology a owl:Ontology;owl:versionInfo "0.5";rdfs:comment “A geospatial instantation of the generic Movement & Path pattern created at GeoVoCampSB2012.";dc:title "Spatial Motions and Paths" .
# Motion classrdfs:comment "A motion is an event in which some entity
moves through space" ;rdfs:subClassOf [
a owl:Restriction;owl:onProperty :startEvent;owl:allValuesFrom event:Event
];:Motion a owl:Class;
rdfs:subClassOf event:Event;rdfs:label "Motion";
rdfs:subClassOf [a owl:Restriction;owl:onProperty :endEvent;owl:allValuesFrom event:Event
];rdfs:subClassOf [
a owl:Restriction;owl:onProperty :path;owl:allValuesFrom :Path
];rdfs:subClassOf [
a owl:Restriction;owl:onProperty spw:hasPart;owl:allValuesFrom :Motion
] ;rdfs:subClassOf [
a owl:Restriction;owl:onProperty :startEvent;owl:allValuesFrom event:Event
] .
A restriction class should have exactly one triple linking the restriction to a particular property, using owl:onProperty.
Orientation to Semantic Methods for Workshop 26
Container in TTL for Owl
@prefix xsd: <http://www.w3.org/2001/XMLSchema#> .
@prefix DUL: <http://localhost/DUL#> . @prefix rdfs: <http://www.w3.org/2000/01/rdf-
schema#> . @prefix daml:
<http://www.daml.org/2001/03/daml+oil#> . @prefix rdf: <http://www.w3.org/1999/02/22-
rdf-syntax-ns#> . @prefix owl:
<http://www.w3.org/2002/07/owl#> . @prefix : <http://localhost/default#> .
:SpatialLocation rdf:type owl:Class .
:Place rdf:type owl:Class ; :IsA :SpatialLocation ; :denotesLocation :Container .
:Container rdf:type owl:Class ; :IsA DUL:SocialObject ; :hasLocation :SpatialLocation .
DUL:SocialObject rdf:type owl:Class .
From CMAP draft