---
tag: SBGXED586X
kind: concept
name: Fluent calculus
sources:
  - wikipedia: en:2961091@r1370052612
    locator: Fluent calculus
    note: adopted
    mention: wikipedia://en/2961091
    sections: [Summary]
same_as:
  wikidata: Q5462656
  wikipedia: Fluent calculus
inventory: [12GTXW0QVW]
---

## Summary

The **fluent calculus** is a formalism for expressing dynamical domains in [[first-order logic|086QKPF0A6]]. It is a variant of the situation calculus. A binary function symbol $\circ$ is used to concatenate the terms that represent facts that hold in a situation. For example, that the box is on the table in the situation $s$ is represented by the formula $\exists t . s = on(box,table) \circ t$. The frame problem is solved by asserting that the situation after the execution of an action is identical to the one before but for the conditions changed by the action. For example, the action of moving the box from the table to the floor is formalized as: