I've been trying to learn about knowledge representations.

According to a canonical definition, a knowledge representation is:

  • a surrogate for real-world entities
  • an ontological commitment about what kinds of entities are relevant

The notion of surrogate is nicely described in the same source:

For any entity (surrogate) in the knowledge representation, we have to be sure we have a good argument for:

  • "correspondence": what does this entity in the KR represent in reality?
  • "fidelity": how well does it match what it is supposed to represent?

Can someone help me think of a useful heuristic to understand what is meant by a surrogate here? The best example I can think of is a map (which has both correspondence and fidelity )

1 Answer 1


Knowledge representation is a model of a certain domain of the real world.

These models are composed from objecttypes (entity, surrogate) and the relations between objecttypes.

Such models are named "ontologies" and can be formalized as "Entity-relationship-models".

Ontologies are used e.g., in business-administration to model a certain business domain. In sales we have entities like customer, order, product and relationsships between the entities customer and order like customer places an order, and between order and product like an order comprises several products. These ontologies are the prerequisites for database design.

  • Ok, thanks- clear. but this describes more about the utility of ontology and Leeds about what a surrogate is. what criteria are used in determining what can be a surrogate?
    – Teusz
    Mar 10, 2016 at 5:48
  • @Teusz I enclose a link to a paper of one of the founders of entity-relationship modeling bit.csc.lsu.edu/~chen/pdf/Chen_Pioneers.pdf An entitytype covers instances with the same attributes, e.g. the entitytype customer covers instances with a name, an address, a solvency etc. Which entitytypes one chooses depends on the aim of the intended model. Only the formal structure of the model is prescribed - not its content.
    – Jo Wehler
    Mar 10, 2016 at 6:23
  • But is an entity type the same thing as a surrogate?
    – Teusz
    Mar 10, 2016 at 6:26
  • 1
    @Teusz I have never heard the term surrogate in the context of data modeling. Your quote introduced the term as a synonym for entity.
    – Jo Wehler
    Mar 10, 2016 at 6:33

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