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Equation 11 · Part 2 · The Hardest Unsolved Problems in Small and On-Device AI

subscript

FiF_i
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

One standard mitigation is regularization: penalize the optimizer for moving parameters that mattered to earlier tasks. The best-known form estimates a per-parameter importance weight — commonly the diagonal of the Fisher information, FiF_i — from the old task, and adds it to the new loss:

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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.