Algernon Tutorial 1.b
Paths, Clauses and Relations

Paths

• A path in a knowledge base is a sequence of frames that are connected by a relation.
• Example 1:
  A mother B brother C cousin D wife E sister F
  F is A's mother's brother's cousin's wife's sister.
• Example 1:
  Gene-1 expresses Protein-7 interactsWith Protein-15 describedIn Publication-475 authoredBy Cohen
  Gene-1 expresses Protein-7 which interacts with Protein-15 which is described in Publication-475 which was authored by Cohen.
• Every input to Algernon must be a path.

Clauses

• A clause specifies the relationship between two frames.
• Example: (Gene-1 -expresses-> Protein-7)
• A frame system expresses that in a FRAME-SLOT-VALUE triple:
  Gene-1
   .  expresses: Protein-7
• Algernon's syntax is like a predicate: (slot frame value).
  Example: (expresses Gene-1 Protein-7).
• A path is a sequence of clauses.

Relations

• Algernon generalizes slot into the general-purpose term relation.
• If you are using the Protege KBMS, the term slot is equivalent to the term relation.

Syntax Summary

• A clause represents one relation.
• Examples:
  • (Color House-7 Green)
  • (name Instance-0039 "Sodium")
  • (Pet Person-1 Cat-7)

• A path is a sequence of clauses.
• Examples:
  • ((Color House-7 Green) (wavelength Green 510.63))
  • ((expresses Gene-1 Protein-7) (interactsWith Protein-7 Protein-15))