Description
Treat a self-loop or a supplied path beginning at to and ending at from as cycleWitness, returning a closed witness list or an empty list.
A walk is an ordered sequence of visited vertices or edges, while a path normally adds structural restrictions. Sequence manipulation and endpoint checks alone do not verify that every required graph edge exists.
Treat a self-loop or a supplied path beginning at to and ending at from as cycleWitness, returning a closed witness list or an empty list.
When to use this tool
Use Edge Role DAG Back Edge Witness when you need a sequence transformation, endpoint comparison, or path-related local calculation.
How to use the tool and how it works
- Enter from, to, reverseReachabilityPath. Use the units and conventions below.
- Run the tool. Correct any format, range, or cross-field input error before interpreting the output.
- Read cycleWitness, witness. Inspect cycleWitness before interpreting the associated values.
Require nonempty from and to and at most 255 reverseReachabilityPath entries. Treat a self-loop or a supplied path beginning at to and ending at from as cycleWitness, returning a closed witness list or an empty list.1
| Input field | Meaning and units | Accepted input |
|---|---|---|
| from | From | Required. Text; maximum UTF-16 length 8192. |
| to | To | Required. Text; maximum UTF-16 length 8192. |
| reverseReachabilityPath | Reverse Reachability Path | Required. Array of text; maximum UTF-16 length 8192; maximum items 256. |
| Output field | Interpretation | Returned shape |
|---|---|---|
| cycleWitness | Cycle Witness | Required. Boolean. |
| witness | Whether the supplied endpoint-shape conditions produce a cycle sequence; intermediate graph edges are not verified. | Required. Array of text; maximum UTF-16 length 8192; maximum items 256. |
{
"input": {
"from": "A",
"to": "B",
"reverseReachabilityPath": [
"B",
"C",
"A"
]
},
"output": {
"cycleWitness": true,
"witness": [
"A",
"B",
"C",
"A"
]
}
}Limitations and assumptions
- Intermediate edges and reachability are not checked, so endpoint agreement alone is only a supplied certificate shape; no DAG validation or graph search is performed.
- 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
Validate each consecutive edge against the graph and check the required path or cycle properties. Use a dedicated traversal or shortest-path algorithm when reachability or optimality is the real question.
References
Similar or alternative tools
- Graph Walk Vertex Occurrence Position
Collect every zero-based position where a walk entry equals vertex and return positions and their count.
- Rooted Tree Preorder Parent Interval Check
Return nested for non-strict containment and proper only when nested and parentStart is strictly earlier.