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Equation 3 · Part 6 · Ten Failure Modes That Define Multimodal AI Systems

subscript

Δ=smulti−stext\Delta = s_{\text{multi}} - s_{\text{text}}
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

The finding motivates a simple, checkable decomposition rather than a new metric: for any multimodal benchmark, let smultis_{\text{multi}} be the score with all modalities present and stexts_{\text{text}} be the same benchmark scored with the non-text modality removed. The quantity Δ=smulti−stext\Delta = s_{\text{multi}} - s_{\text{text}}. is the actual multimodal increment — what the removed channel contributed beyond what text alone already bought. A large smultis_{\text{multi}} with a small Δ\Delta is not evidence of multimodal competence; it is evidence that the benchmark, not the model, is doing something unimodal. Reporting Δ\Delta alongside smultis_{\text{multi}} costs one extra evaluation run and turns an unfalsifiable headline number into a…

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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.