2. (Stochastic Gradient Descent) Let us assume the function f(x) can be written as: f(x) = f(x), i=1 where fi, f2f are L-smooth convex functions. Let i be a random variable uniformly distributed in {1, 2,...,n}. Then prove that E[||Vf; (x) – Vfi (x*)||₁₂] ≤ 2L(f(x) − f(x*)), where the expectation is taken with respect to the randomness i. Hint: You can assume that for any L-smooth convex function h the following holds: Lemma 2 (Convexity and smoothness). For all x, y = Rd ||Vh(x) - Vh(y)||≤ 2L (h(x)-h(y) - Vh(y) (x − y)).

Advanced Engineering Mathematics
10th Edition
ISBN:9780470458365
Author:Erwin Kreyszig
Publisher:Erwin Kreyszig
Chapter2: Second-order Linear Odes
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2. (Stochastic Gradient Descent) Let us assume the function f(x) can be written as:
f(x) = f(x),
i=1
where fi, f2f are L-smooth convex functions. Let i be a random variable uniformly distributed in {1, 2,...,n}.
Then prove that
E[||Vf; (x) – Vfi (x*)||₁₂] ≤ 2L(f(x) − f(x*)),
where the expectation is taken with respect to the randomness i.
Hint: You can assume that for any L-smooth convex function h the following holds:
Lemma 2 (Convexity and smoothness). For all x, y = Rd
||Vh(x) - Vh(y)||≤ 2L (h(x)-h(y) - Vh(y) (x − y)).
Transcribed Image Text:2. (Stochastic Gradient Descent) Let us assume the function f(x) can be written as: f(x) = f(x), i=1 where fi, f2f are L-smooth convex functions. Let i be a random variable uniformly distributed in {1, 2,...,n}. Then prove that E[||Vf; (x) – Vfi (x*)||₁₂] ≤ 2L(f(x) − f(x*)), where the expectation is taken with respect to the randomness i. Hint: You can assume that for any L-smooth convex function h the following holds: Lemma 2 (Convexity and smoothness). For all x, y = Rd ||Vh(x) - Vh(y)||≤ 2L (h(x)-h(y) - Vh(y) (x − y)).
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