Contract-Based Agentic Systems Engineering: Delegation as Quotient for Assured System Design
Organizations: Department of Electrical and Computer Engineering and the Institute for Systems Research, University of Maryland, College Park, MD 20742, USA
Abstract
A component an agent builds from a prompt can satisfy it and still break the system it joins, because the prompt omits what its neighbours assume of it. The artifact to hand over is computed, not written. A SysML v2 requirement with assumed and required constraints is an assume/guarantee contract, so when a system requirement is decomposed over fixed neighbours, the open component's requirement is the contract quotient, the weakest sound one, and again a SysML v2 requirement. Its required constraints carry the neighbours' assumptions, which a requirement for the mission alone drops and unit tests with mocked neighbours cannot reach. Signal Temporal Logic is closed under the quotient. We build the requirements, with derivation, allocation, satisfaction and verification, as a SysML~v2 model and compute the quotient from it. A case study delegates the local controller of a simulated warehouse robot, whose route crosses a worker's path and ends at a dock, to one language model under the quotient requirement, a mission-only requirement and a natural-language task, and scores the deliveries on live episodes against the system requirement from ground truth.
Figures & tables
| Symbol | Meaning | Symbol | Meaning |
|---|---|---|---|
| true clearance now, robot body to nearest point of the person’s body; its smallest value up to the next tick | required clearance | ||
| true clearance at the observation time of the report in hand | , | tolerances of the drive’s displacement and of the person’s closing | |
| reported clearance, to the nearest reported person point | closing speed of the person’s body | ||
| time since the observation in hand was measured; the time from the tick to the next control tick | , | magnitudes of the commanded speed and yaw rate ( v , w in the listings) | |
| bound on in view, the perception error | , | position and heading error of the pose estimate | |
| largest commanded speed in effect over the age and the drive’s 0.15 s lag before it, times the age; the same with the age counted to the next tick | , | distance and heading error to the dock, true or estimated ( , ; g_est in the listings) |
| Clause | Bound | Set by |
| System assumes | ||
| approach | and | largest limb closing measured, 1.385 m/s |
| blind side | nobody within 0.40 out of view, now and to the next tick | the camera’s field of view |
| frames | a scan and a people record every 0.5 | sensor rates |
| walk | crosses once, within 0.72 of its segment, back at most 0.72 | the drawn walks |
| route | the route 1.4 from mapped surfaces | the warehouse layout |
| Delivery | Admitted by its own harness | Safe at the bounds | Live, 30 standard | Live, at the edge | Closest |
|---|---|---|---|---|---|
| agent, derived requirement | yes | yes | 30 of 30 | 4 of 4 | 1.42 m |
| agent, mission-only | yes | yes | 30 of 30 | not run | 1.57 m |
| agent, mission-only, resampled | yes | no, breaks 8 of 482 | 30 of 30 | 16 of 22 | 0.14 m |
| agent, natural language | yes, by its own scoring | yes | 30 of 30 | not run | 1.22 m |
| reference, hand-written | yes, under all three | yes | 30 of 30 | not run | 1.56 m |
| witness, written to the mission-only letter | yes, by the first mission-only harness | no | 0 of 30 | not run | contact in 29 |
| Variant | Changed bound | GT | Q | D | M |
|---|---|---|---|---|---|
| as declared | age 0.40 s, rest error 0.05 m | 24 | 24 | 12 | 120 |
| slower perception | age 0.80 s | 12 | 12 | 0 | 120 |
| faster perception | age 0.20 s | 24 | 24 | 12 | 120 |
| coarser map | rest error 0.20 m | 0 | 0 | 0 | 120 |
Requirements Engineering
Requirements engineering studies how stakeholder needs are elicited, specified, analyzed, validated, and traced into dependable systems.
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