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Equation 16 · Part 2 · The Hardest Unsolved Problems in Frontier AI Model Comparisons

subscript

δi,b\delta_{i,b}
subscript

What this part means

The lower label selects a particular version, component, or indexed member of the quantity. For example, x₀ and xₜ can be values at different positions.

Its job in the formula

A subscript distinguishes a version, component, step, or member of a quantity. It does not automatically mean multiplication.

The passage around this formula

Even a single benchmark’s score is compromised if the term δi,b\delta_{i,b} above is nonzero: if some of what looks like reasoning is actually recall of a benchmark item, or an item closely resembling it, that appeared in the model’s training data. Public benchmarks such as GSM8k have been circulating on the open web for years, meaning they, and countless worked solutions and discussions of them, are plausible components of any large modern pretraining corpus.

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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 →

Sources cited in the article section

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