Schema

From Freebase

We use the term Schema to refer to the way Freebase's data is laid out or structured. In the Semantic web world, this is referred to as Ontology.

Schema in Freebase is expressed through Types and Properties. Types are grouped together in Domains.

Anyone may create schema in Freebase. Simply create a base and make types within that base, then edit them using the Schema editor.

For more information/help with developing Freebase Schema, join the Data-modeling mailing list.

Glossary

• CVT
• Phylogeny pattern
• Sibling pattern
• Expected type
• Time mediation pattern

Tools

• Schema Explorer
• Schema Visualization tool

Guidelines

Commons Criteria

The following is a list of items which would be expected to be seen in a base schema which was proposed for promotion to the commons. These are not a strict requirement, but just a guideline:

• The schema is of broad appeal and use
  • The schema is likely to be included in other bases, and/or
  • There are a lot of untyped topics in Freebase which could use these types, and/or
  • There are multiple known uses cases for using the data in apps
• The schema in not overly abstract or complex.
  • In most cases, the schema should be understandable by a knowledgeable lay-person
• All types and properties are documented, possibly also including an example of typical use and where not to be used.
• Types include relevant commons types. e.g. a newsletter type would include the periodical type from the commons.
• CVTs and enumerations are used appropriately.
• Numeric properties should typically be either unique or use a CVT with a date property (e.g., be date-mediated).
• Date/time properties should typically be unique.
• Included types and expected types are from the base or the commons.
• Properties are reciprocated where appropriate. (An exception can be made for properties that expect a commons type, and which will be reciprocated upon promotion.)
• Expected types of properties are specific. I.e. a pilot, not a person, flies a plane (but pilot would include person).
  • Types to avoid: person, location
• Types and Properties follow naming conventions.
• Properties flagged as disambiguators have been selected carefully.
• You are prepared to take responsibility for helping to maintain the common in the future, or have delegated to someone appropriate.

Location

A simple method to determine whether a topic IS-A or HAS-A Location is whether it is likely to move. If it is fixed (such as a building or mountain) it IS-A Location, if it can move (a company's place of business, or a person's place of residence) it HAS-A Location.