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Transcript of Graph Databases
A graph database is essentially a collection of nodes and edges.
Uses graph theory to store, map and query relationships
7 Bridges of Königsberg. - Leonhard Euler
The IBM Information Management System (IMS)
Commercial graph DB from 2003
LinkedIn uses its own graph db
Initially used by twiter FlockDB
Apache Giraph - Facebook uses this
from w3c.org - Bigdata® is a standards-based, high-performance, scalable, open-source graph database.
Clustering for read
RETURN n, m;
MATCH (n)-->( )
RETURN actor.name, movie.title;
SNOMED CT consists of four primary core components:
Concept Codes - numerical codes that identify clinical terms, primitive or defined, organized in hierarchies
Descriptions - textual descriptions of Concept Codes
Relationships - relationships between Concept Codes that have a related meaning
Reference Sets - used to group Concepts or Descriptions into sets, including reference sets and cross-maps to other classifications and standards.
SNOMED CT's relational statements are basically triplets of the form Concept1 - Relationx - Concept2, with Relationx being from a small number of relation types (called linkage concepts)
e.g. finding site, due to, etc. The interpretation of these triplets is (implicitly) based on the semantics of a simple Description logic (DL).
E.g., the triplet Common Cold - causative agent – Virus, corresponds to the first-order expression
forall x: instance-of (x, Common cold) -> exists y: instance-of (y, Virus) and causative-agent (y, x)
or the more intuitive DL expression
Common cold subClassOf causative-agent some Virus
1) "Is A" Relationship
The “Is A” relationship is used to create a hierarchical relationship between concepts, relating
specific concepts to a more general category. For example:
"Injury to the optic nerve"
"is a" (kind of)
"Injury to the visual pathway"
2) "Finding Site" Relationship
The "Finding Site" relationship identifies the part of the body affected by the specific disorder or
finding. For example:
"Injury of cornea"
(has) "finding site"