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Equation 7 · Part 5 · Building a Multimodal AI Application That Actually Uses Its Inputs

subscript

Δm=Accfull−Accablate(m).\Delta_m = \mathrm{Acc}_{\mathrm{full}} - \mathrm{Acc}_{\mathrm{ablate}(m)}.
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 formal version is a simple, reportable metric. For a task with a full-input accuracy Accfull\mathrm{Acc}_{\mathrm{full}} and an accuracy Accablate(m)\mathrm{Acc}_{\mathrm{ablate}(m)} measured with modality m removed, blanked, or replaced with noise, define Δm=Accfull−Accablate(m)\Delta_m = \mathrm{Acc}_{\mathrm{full}} - \mathrm{Acc}_{\mathrm{ablate}(m)}. A small Δm\Delta_m for a modality the task specification says should matter is the signature of a unimodal shortcut: the model is scoring well on the full-input evaluation without actually depending on that channel. This is not a hypothetical failure mode. Agrawal and colleagues showed that VQA models trained and evaluated under the field’s original data splits could reach strong scores while relying heavily on the language prior in…

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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 surrounding passage

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