General Definitions

Graph Store

Definition: Graph Store

A Graph Store GS is a mutable container of RDF graphs. It has one unnamed (default) slot and zero or more named slots. The unnamed slot holds an RDF graph; each named slot is a pair of a graph and an associated IRI. The Graph Store can be viewed as a mutable RDF Dataset.

GS = {DG, (iri1, G1), ... , (irin, Gn) }

where

• the default graph DG is the RDF graph associated with the unnamed slot
• n ≥ 0 and for each 1 ≤ i ≤ n, Gi is an RDF graph associated with the named slot identified by IRI irii
• all IRIs are distinct, i.e., i≠j implies irii≠irij

Note:

We will use GS for the Graph Store, but sometimes also - synonymously - for the RDF Dataset corresponding to the current Graph Store content in subsequent definitions. For convenience, we will also sometimes write GS = {DG} union {(iri

i, G

i) | 1 ≤ i ≤ n} as an alternative mathematical notation for GS = {DG, (iri

1, G

1), ... , (iri

n, G

n) } in subsequent definitions.

Abstract Update Operation

Definition: Update Operation

An Update Operation Op is an atomic operation that accepts some arguments Args and transforms a Graph Store GS to another Graph Store GS', denoted as

Op(GS, Args) = GS'

By 'atomic operation' we mean that the operation performs the described transformation of the Graph Store either completely or leaves the Graph Store unchanged, i.e., the result is either GS' or GS (in case of error).

An Update Operation can create new slots and new RDF graphs, or can remove existing slots and the corresponding graphs. It can also alter the state of each slot individually.

We will define the semantics of each concrete update operation in terms of concrete instances of this abstract update operation definition.