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Equation 19 · Part 2 · The Hardest Unsolved Problems in Small and On-Device AI

Symbol delta

(ε,δ)(\varepsilon, \delta)
δ\delta

What this part means

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

Its job in the formula

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

The passage around this formula

…even though raw data stays local [ 7 ] . Its response is differential privacy: each client “locally clips and perturbs its LoRA matrices using Gaussian noise” before anything is sent, with a formal (ε\varepsilon, δ\delta) -differential-privacy guarantee attached [ 7 ] . That noise is not free — it is a second trade-off, alongside the memory one, between how much personalization signal survives and how strong the privacy guarantee is.

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