Equation 4 · Part 1 · Why Coding Agents Fail: Long-Horizon Reliability in OpenAI Codex

Symbol a_t

a_t

a_t

What this part means

the action.

Its job in the formula

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

Full expressionSymbol a_tArticle meaning

Where the article explains it

where $s_t$ is environmental state, $o_t$ the agent’s observation, and $a_t$ its action.

The passage around this formula

where $s_t$ is environmental state, $o_t$ the agent’s observation, and $a_t$ its action. Task success is not a property of the final message. It is an externally evaluated predicate V( $s_T$ ,g) over final state and goal g . System reliability under task distribution D is

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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.

Open the illustrated subscripts: which member of a family? guide →

See this notation across published equations →

Sources cited in the article section

[2] Introducing GPT-5.3-Codex ↗

These citations provide research context; check each source for the exact claim it supports.