Implementing temporal constraints

[JasperHavenhand]

Need to find how to restrict temporal reachability and temporality of a graph within Gradoop.

[JasperHavenhand]

The temporal reachability can be limited by a number of methods: merging, delaying, and edge and label deletion.

[JasperHavenhand]

Merging:

• Single parameter, λ.
• For a given temporal graph, let E_t be the set of edges with a label for time t.
• Set the first (λ-1)^th edge sets (E₀ - E_λ-1) equal to empty sets and the λth edge set equal to the union of all λ edge sets.
• In other words, set all labels younger than the λ^th timestep equal to λ.

Need to work out how this could be adapted for time ranges.

[JasperHavenhand]

A potential way to adapt the merging to time ranges is to use another parameter, the duration. That is, find all edges whose validFrom time is before λ, set their validFrom time to λ, and set their validTo time to λ plus the specified duration. This will maintain the purpose of merging which is to prevent it being possible to create a temporal path across the affected edges. This will also reduce the number of edges, in turn reducing the execution time for operations on the graph.

[JasperHavenhand]

Sampling could be useful for the deletion methods.

[JasperHavenhand]

43d8fd7f80891687cf99d9cd63b30393a3ef0be3 The delay edges method has been added.

[JasperHavenhand]

Reducing temporality, i.e., reducing the number of labels on each theoretical edge, seems the most logical next task. In the actual implementation, there is a separate edge for each label so reducing this will help with processing times.

[JasperHavenhand]

A method for limiting the temporality has been implemented.

[JasperHavenhand]

A method for deleting edges can be easily implemented by adapting the limitTemporality method.

[JasperHavenhand]

54e0a3a5b60d105d19a7cbf3579d81122127a709 Added the deletion method.