How to Use the Knowledge Graph

The Knowledge Graph is the KBpedia knowledge structure, which itself combines six public knowledge bases — Wikipedia, Wikidata, GeoNames, OpenCyc, DBpedia and UMBEL — and their concepts, entity types, attributes and relations.

This combined KBpedia knowledge structure contains more than 54,000 reference concepts (RCs), organized into a knowledge graph as defined by the KBpedia Knowledge Ontology. KKO is a logically organized and computable structure that supports inference and reasoning.

 
 

About 85% of the RCs are themselves entity types — that is, 46,000 natural classes of similar entities such as astronauts or marigolds — which are organized into about 30 "core" typologies that are mostly disjoint (non-overlapping) with one another.

KBpedia's typologies provide a powerful means for slicing-and-dicing the knowledge structure. The individual entity types provide the tie-in points to about 20 million individual entities. The remaining RCs are devoted to other logical divisions of the knowledge graph, specifically attributes, relations and topics.

It is this structure, plus often connections to another 20 leading external vocabularies, that forms the basis of the KBpedia Knowledge Graph.

Search

There are many search options for the knowledge graph. See the separate Knowledge Graph Search document for instructions on the search functions.

RC Record

Each RC Record has potentially eight (8) main panels or sections:

  • Header
  • Core Structure
  • Extended Linkages
  • Typologies
  • Entities
  • Aspect-related Entities
  • Broader Concepts
  • Narrower Concepts.

Panels are only displayed when there are results for them.

The untitled Header consists of these possible entries:

  • prefLabel - URI - image — the prefLabel is the name or "title" for the RC. While the name has no significant meaning in and of itself (the meaning for the RC is a result of all specifications and definitions, including relations to other objects, for the concept), the prefLabel does provide a useful shorthand or handle for referring to the concept. The URI is the full Web reference to the concept, such as http://kbpedia.org/kko/rc/Mammal. If there is an image for the RC, it is also displayed
  • semset — the entries here, also known as altLabels, are meant to inclusively capture all roughly equivalent references to the concept, including synonyms, slang, jargon and acronyms
  • definition — the readable text definition or description of the RC; some live links may be found in the definition.

Core Structure

The Core Structure for KBpedia is derived from six (6) main knowledge bases — OpenCyc, UMBEL, GeoNames, DBpedia, Wikipedia and Wikidata. The conceptual relationships in the KBpedia Knowledge Ontology (KKO) are largely drawn from OpenCyc and UMBEL, though any of the other four sources may contribute local knowledge graph structure. Additional reference concepts (RCs) are contributed primarily from GeoNames and Wikipedia. Wikidata contributes the bulk of the instance data, though instance records are actually drawn from all sources. DBpedia and Wikidata are also the primary sources for attribute characterizations of the instances.

Two characteristics define what is a core contributor to the KBpedia structure: 1) the scale and completeness of the source; and 2) its contribution of a large number of RCs to the overall KKO knowledge graph. The KBs in the core structure play a central role in the scope and definition of KBpedia. This core structure of KBpedia is supplemented by mappings to about 20 additional external linkages, which are highly useful for interoperability purposes, but do not themselves contribute to the same extent to the RC scope of the KKO graph.

General Use

The Core Structure panel begins by providing an option for viewing RCs as either Direct or Inferred. Let's defer that discussion for a moment until the next sections. For either option, how we use this panel remains the same.

Relations for RCs within the KKO graph may be equivalent (owl:equivalentClass), a parent super class (kko:superClassOf), a child sub class (rdfs:subClassOf), or a closely related concept (kko:isCloselyRelated). These relationships define the edges between the nodes in the graph structure, and are also the basis for logical inferencing.

Depending on which of these four (possible) relations you chose, the related concepts are presented as direct or inferred mappings to one of the six core sources for KBpedia (OpenCyc, UMBEL, GeoNames, DBpedia, Wikipedia or Wikidata). Live links are shown for these RCs to the constituent source with its accompanying icon.

For RCs that are entity types, the entry might also display the count of entities (blue background with count) or related-aspect entities (orange background with count) linked to that RC (either directly or inferred, depending on the option chosen). Clicking on the specific RC link will take you to that reference concept. Clicking on the highlighted background will take you to a listing of the entities for that RC (based on either its direct or inferred option).

Direct

Sub-classes and Super-classes may be determined either as direct assertions or those that are inferred from parent-child relationships in the Knowledge Graph. Picking this sub-tab restricts the display to only the RCs that are directly asserted in the KBpedia Knowledge Ontology (KKO).

Inferred

Sub-classes and Super-classes may be determined either as direct assertions or those that are inferred from parent-child relationships in the Knowledge Graph. Picking this sub-tab broadens the display to all of the RCs that are inferred from the parental or child lineage of the current RC. Like familial relationships, the closer the concept is to its lineage relation, the likely closer are the shared attributes or characteristics of the concepts. Such lineage inferences arise from the relations in the KBpedia Knowledge Ontology (KKO).

External Linkages

KBpedia reference concepts (RCs) are linked to thousands of classes defined in nearly 20 external ontologies used to describe all kinds of public and private datasets. Some of the prominent external vocabularies include schema.org, the major structured data system for search engines, and Dublin Core, a key vocabulary from the library community. Other external vocabularies cover music, organizations, projects, social media, and the like.

General Use

The External Linkage panel begins by providing an option for viewing RCs as either Direct or Inferred. Let's defer that discussion for a moment until the next sections. For either option, how we use this panel remains the same.

Relations for RCs within the KKO graph may be equivalent (owl:equivalentClass), a parent super class (kko:superClassOf), a child sub class (rdfs:subClassOf), or a closely related concept (kko:isCloselyRelated). These relationships define the edges between the nodes in the graph structure, and are also the basis for logical inferencing.

Depending on which of these four (possible) relations you chose, the related concepts are presented as direct or inferred mappings to one of the 20 or so external vocabularies and schema to which KBpedia is mapped. Live links are shown for these RCs to the constituent source with its accompanying icon.

For RCs that are entity types, the entry might also display the count of entities (blue background with count) or related-aspect entities (orange background with count) linked to that RC (either directly or inferred, depending on the option chosen). Clicking on the specific RC link will take you to that reference concept. Clicking on the highlighted background will take you to a listing of the entities for that RC (based on either its direct or inferred option).

Direct

Sub-classes and Super-classes may be determined either as direct assertions or those that are inferred from parent-child relationships in the Knowledge Graph. Picking this sub-tab restricts the display to only the RCs that are directly asserted in the KBpedia Knowledge Ontology (KKO).

Inferred

Sub-classes and Super-classes may be determined either as direct assertions or those that are inferred from parent-child relationships in the Knowledge Graph. Picking this sub-tab broadens the display to all of the RCs that are inferred from the parental or child lineage of the current RC. Like familial relationships, the closer the concept to its lineage complement, the likely closer are the shared attributes or characteristics of the concepts. Such lineage inferences arise from the relations in the KBpedia Knowledge Ontology (KKO).

Entities

Entities are distinct, nameable, individual things. Entities may be physical objects or conceptual works or discrete ideas, so long as they may be characterized by attributes shared by other instances. Entities may be parts of other things, so long as they have a distinct identity and character. Entities with shared attributes that are the essence of the things may be grouped into natural types, called entity types. These entity types may be further related to other entity types in natural groupings or hierarchies depending on the attributes and their essences that are shared among them.

Nearly 85%, or 30,000, of the reference concepts within the KBpedia Knowledge Ontology (KKO) are entity types, these natural classes of entities. They are key leverage points for inteoperability and mapping.

General Use

Instances (or entities) are related to the KKO graph via the rdfs:type predicate, which assigns an entity to one or more parental classes. It is through this link that you view entities.

For the current RC, which is by definition an entity type, we first display the count of entities that may be reached from this point, plus then a small listing of matching entities. These sample entities may be clicked and viewed as Entity Records, or you may browse all entities for this RC by clicking the Browse all entities button.

Entities may be characterized according to one or more of about 80 aspects. Aspects help to group related entities by situation, and not by identity nor definition. Aspects thus provide a secondary means for organizing entities independent of their nature, but helpful for placing the entity in real-world contexts. Not all aspects relate to a given entity.

If an entity with a related aspect occurs in the knowledge system, its aspect label will be shown with then a listing of the top entities for that aspect. Each of these entities is clickable, which will take you to the standard entity record. A button to Browse all entities means there are more entities for that aspect than the short listing will allow; click on it to be able to paginate through the full listing of related entities.

Typologies

About 85% of all of the reference concepts (RCs) in KBpedia represent classes of entities, which themselves are organized into about 30 core typologies. Most of these typologies are disjoint (lack overlap) from one another, which provides an efficient mechanism for testing subsets and filtering entities into smaller groups for computational purposes. (Another 50 or so SuperTypes provide extended organization of these entities.)

The major groupings of types reside in core typologies, which is where the largest degree of disjointedness occurs. There are some upper typologies (such as Living Things over Plants, Animals, etc.) that are used mostly for organizational purposes. The core typologies are the key ones to focus upon for distinguishing large groupings of entities.

Core

The KBpedia typologies, also known as SuperTypes, are split into two categories. The main category, "core," contains the typologies with the most RC members. The core typologies are where most of the entities are disjoint, and represents a key resource for effective slicing-and-dicing of the knowledge base.

If the current RC belongs to one of more of the core typologies, it is shown in this section.

Extended

Another 50 or so SuperTypes are also used to help organize the upper structure above these core typologies. Most of these additional SuperTypes have few RC members and less disjointedness (have more overlap) with other typologies. Though they are useful for placing the entity types into context, these 50 "extended" typologies are less useful for computing purposes. They are thus segregated into this section section.

If the current RC belongs to one of more of the extended typologies, it is shown in this section.

Broader Concepts

Broader concepts represent the parents (or grandparental lineage in the case of inference) for the current reference concept (RC). The broader concept relationship is expressed using the transitive kko:superClassOf property. This property is the inverse of the rdfs:subClassOf property.

All applicable broader concepts are listed in this panel. If the RC is an entity type, it may also show counts for all entities subsumed under that type (orange color) or that have aspects of that type (blue color). Clicking on these count icons will take you to a listing of these entities.

Direct

Sub-classes and Super-classes may be determined either as direct assertions or those that are inferred from parent-child relationships in the Knowledge Graph. Picking this sub-tab restricts the display to only the RCs that are directly asserted in the KBpedia Knowledge Ontology (KKO).

Inferred

Sub-classes and Super-classes may be determined either as direct assertions or those that are inferred from parent-child relationships in the Knowledge Graph. Picking this sub-tab broadens the display to all of the RCs that are inferred from the parental or child lineage of the current RC. Like familial relationships, the closer the concept to its lineage complement, the likely closer are the shared attributes or characteristics of the concepts. Such lineage inferences arise from the relations in the KBpedia Knowledge Ontology (KKO).

Narrower Concepts

Narrower concepts represent the children (or grandchild lineages in the case of inference) for the current reference concept (RC). The narrower concept relationship is expressed using the transitive rdfs:subClassOf property. This property is the inverse of the kko:superClassOf property.

All applicable narrower concepts are listed in this panel. If the RC is an entity type, it may also show counts for all entities subsumed under that type (orange color) or that have aspects of that type (blue color). Clicking on these count icons will take you to a listing of these entities.

Direct

Sub-classes and Super-classes may be determined either as direct assertions or those that are inferred from parent-child relationships in the Knowledge Graph. Picking this sub-tab restricts the display to only the RCs that are directly asserted in the KBpedia Knowledge Ontology (KKO).

Inferred

Sub-classes and Super-classes may be determined either as direct assertions or those that are inferred from parent-child relationships in the Knowledge Graph. Picking this sub-tab broadens the display to all of the RCs that are inferred from the parental or child lineage of the current RC. Like familial relationships, the closer the concept to its lineage complement, the likely closer are the shared attributes or characteristics of the concepts. Such lineage inferences arise from the relations in the KBpedia Knowledge Ontology (KKO).

Browse Entities

This KBpedia reference concept (RC) is a type, or class, of one or more similar entities. The Browse Entities panel repeats the reference to the source RC, and then lists entities that belong to that type in paginated groups of twenty. An entity appears on this lists either because: 1) it is asserted to belong to that class, or 2) it is inferred to belong to that class according to relationships with other KBpedia reference concepts or external sources.

Each entity listed in the table is presented via its preferred label and its description. Clicking on one of the entity links will take you to its Entity Record report.

If you want to refresh the information about the source RC, click on the Check concept's definition button to go back to the RC Record report. [Button]

Entity Record

The Entity Report provides the structured data and linkages for the 20 million or so entities within the KBpedia system. The Entity Report has four main panels or sections:

  • Export Structured Data
  • KBpedia Types
  • KBpedia Aspects
  • Entity's Structured Data

Export Structured Data

The Export Structured Data panel enables you to export the current entity record in a variety of formats.

The structured data for KBpedia's knowledge base entities may be exported in the formats of JavaScript object notation (JSON), Resource Description Framework in XML format (RDF+XML), RDF in Notation 3 format (RDF+N3), or Extensible Data Notation (EDN, a Clojure format). A variety of other formats are commercially available, and others may be implemented upon request.

KBpedia Types

Types are classes of similar entities, as determined mostly by shared attributes. Most of the nodes (or reference concepts or RCs) within the KBpedia Knowledge Ontology (KKO) are types. Types thus provide important entry points into the KKO knowledge graph. Types, due to their structural relationship with other types and concepts, may be used to infer more facts about the entity, or to place the entity into context with respect to the overall knowledge graph. More than 30,000 types presently exist within the KKO graph, organized into about 30 broad typologies.

The KBpedia Types panel presents a listing of the various entity types to which the current entity belongs. Clicking one of these entity type links will take you to a RC Record report. Also, counts for the number of entities subsumed under each type are provided in the orange icon. Clicking on it brings you to the standard Browse entities display, where you may scroll through and pick other entities for viewing.

KBpedia Aspects

Aspects are related characterizations of entities that help provide additional context for the item. Aspects help to situate the entity within location, time, or any of the other 80 standard aspects. Unlike types, which define what kind of thing or class the entity is, aspects help to group related entities by situation, and not by identity nor definition. Aspects thus provide a secondary means for organizing entities independent of their nature, but helpful for placing the entity in real-world contexts.

The KBpedia Aspects panel presents a listing of the various entity types to which the current entity shares an aspect. Clicking one of these entity type links will take you to a RC Record report.

Entity's Structured Data

All of the entities within KBpedia are characterized by structured data. Structured data includes the attributes, labels and descriptors for the entity. Collectively, these are known as properties. Depending on the entity, there may be many items in this structured data characterization.

Primary sources for the structured data include DBpedia, Wikipedia, and Wikidata. More than 6000 properties are included in these sources, though, of course, only a minor portion apply to any given entity. The Wikidata properties are noted by the 'P' prefix; mouse over the label to see a text explanation of the property. All non-Wikidata properties have standard labels.

The Entity's Structured Data panel provides a (potentially) rich variety of structured data for the current entity. This structured data combines information from any of the core KBpedia knowledge bases. The scope and exact nature of the structured data provided for the entity depends on what exists within these core KBs. Standard HTML metadata is common, as well as key-value attribute values from the constituent entity records.

As a result, the list of possible structured data items that may be shown numbers into the hundreds, though typically only a much smaller set is found for any given entity. Inspect a few different entity records to see the diversity of items that may be covered.