Description
Count one contribution for each endpoint equal to vertex, so a loop at that vertex contributes two.
A graph's degree records how many edge incidences meet a vertex. Directed edges distinguish incoming and outgoing incidences, while loops and parallel edges require explicit counting conventions; a local degree formula does not reconstruct a graph.
Count one contribution for each endpoint equal to vertex, so a loop at that vertex contributes two.
When to use this tool
Use Undirected Edge Stub Count Contribution when you need a degree or incidence calculation under the stated graph convention.
How to use the tool and how it works
- Enter source, target, vertex. Use the units and conventions below.
- Run the tool. Correct any format, range, or cross-field input error before interpreting the output.
- Read degreeContribution, loop. Inspect loop before interpreting the associated values.
Count one contribution for each endpoint equal to vertex, so a loop at that vertex contributes two. Report loop independently when source equals target.1
| Input field | Meaning and units | Accepted input |
|---|---|---|
| source | Source | Required. Text; maximum UTF-16 length 8192. |
| target | Target | Required. Text; maximum UTF-16 length 8192. |
| vertex | Vertex | Required. Text; maximum UTF-16 length 8192. |
| Output field | Interpretation | Returned shape |
|---|---|---|
| degreeContribution | Degree Contribution | Required. Safe integer. |
| loop | Loop | Required. Boolean. |
{
"input": {
"source": "a",
"target": "a",
"vertex": "a"
},
"output": {
"degreeContribution": 2,
"loop": true
}
}Limitations and assumptions
- A loop elsewhere has loop true and zero degreeContribution; this is one literal undirected edge record, without verifying graph membership or degree totals.
- Inputs must satisfy both the field types and the cross-field conditions above. Invalid input causes an error; a successful false flag or documented placeholder is a different result.
Alternative or Complementary methods
Build an adjacency structure and count actual incidences when a full graph is available. Validate loop, multiplicity, direction, and vertex-set assumptions before applying a simple-graph identity.
References
Similar or alternative tools
- Vertex Loop Degree Contribution
Give each loop two degree contributions in an undirected graph or total directed degree, and one when directed and counting a single directed-degree side.
- Directed Edge Source Target Incidence Sign
Return one when vertex matches target, minus one when it matches source, with cancellation for a self-loop.