Canonical terms
These are the project definitions used across the research site.
Agent
A temporally persistent system that maps observations and internal state to actions in an environment according to a policy, in service of an objective. Russell & Norvig ; Sutton & Barto ; Åström & Murray
Single agent
One decision-making system acting on one environment. Sutton & Barto ; Åström & Murray
Policy
The rule or function that maps decision state to action. Sutton & Barto ; Åström & Murray
Objective
The latent criterion of success that the system is trying to achieve. Russell & Norvig ; AERA/APA/NCME validity standards overview
Goal
What counts as success for the system. Russell & Norvig ; Sutton & Barto
Environment
The world or system the agent interacts with and can affect. Russell & Norvig ; Sutton & Barto
Observation
What the agent receives from the environment. Åström & Murray ; Sutton & Barto
State
The information the agent uses to decide. State may include current observations, internal variables, estimates, and memory. Sutton & Barto ; Åström & Murray
Memory
Retained state across steps. This includes short-term context, long-term traces, prior task progress, and learned heuristics. Sutton & Barto ; POMDP belief-state framing
Action
What the agent does to affect the environment. Russell & Norvig ; Sutton & Barto
Error
The gap between current behavior or outcome and desired behavior or outcome. Åström & Murray ; optimal control framing
Steering
Changing behavior in response to error and feedback. Åström & Murray
Measurement
The observable signal produced by tests, traces, audits, judges, sensors, or logs. Cronbach & Meehl ; AERA/APA/NCME validity standards
Proxy
A measurable stand-in for the objective. Cronbach & Meehl ; Goodhart’s law overview
Evaluation
The function that aggregates measurements and proxies into a score or decision signal. AERA/APA/NCME validity standards ; balanced scorecard framing
Control input
A deliberate change applied to steer the system. Åström & Murray
Controller
The mechanism that selects control inputs or actions. Åström & Murray ; Sutton & Barto
Dynamics
How actions and environment evolution change future state. Åström & Murray
Feedback loop
Observe → interpret → decide → act → update. Åström & Murray
Stability
Whether the system converges, oscillates, or diverges under feedback. Åström & Murray
Robustness
Whether the agent still works under noise, delay, partial observability, or perturbation. Åström & Murray
Partial observability
When the agent cannot directly see the full state of the environment. POMDP framing ; Åström & Murray
Estimation
Inferring hidden or incomplete state from observations. Åström & Murray
Policy update
A change to the policy based on experience, learning, or feedback. Sutton & Barto ; adaptive control framing
Model
A representation of how the environment or system behaves. Russell & Norvig ; Åström & Murray
Goodhart effect
When optimization pressure causes a proxy to stop tracking the true objective well. Goodhart’s law ; variants of Goodhart’s law
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