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Equation 5 · Part 1 · Claude Code, From First Principles: The Agentic Loop, Permissions, and What Actually Executes

Symbol a_t

ata_t
ata_t

What this part means

ata_t is a part of this expression. Its role is fixed by the surrounding article and by the operations shown in the formula.

Its job in the formula

ata_t is a part of this expression. Its role is fixed by the surrounding article and by the operations shown in the formula.

The passage around this formula

Let ctc_t be the context available to the model at step t : system instructions, conversation so far, file contents, tool outputs. The model is a policy π\pi that, given ctc_t , emits either a final answer or a tool call ata_t :

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Learn the underlying idea

A subscript is a label attached below a symbol. It often selects a time step, component, category, or member of a sequence.

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Sources cited in the article section

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