The Complexity of Gradient Descent: CLS = PPAD boolean AND PLS



Fearnley, John, Goldberg, Paul, Hollender, Alexandros and Savani, Rahul ORCID: 0000-0003-1262-7831
(2023) The Complexity of Gradient Descent: CLS = PPAD boolean AND PLS. .

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Abstract

We study search problems that can be solved by performing Gradient Descent on a bounded convex polytopal domain and show that this class is equal to the intersection of two well-known classes: PPAD and PLS. As our main underlying technical contribution, we show that computing a Karush-Kuhn-Tucker (KKT) point of a continuously differentiable function over the domain [0,1]2 is PPAD ∩ PLS-complete. This is the first non-artificial problem to be shown complete for this class. Our results also imply that the class CLS (Continuous Local Search) - which was defined by Daskalakis and Papadimitriou as a more "natural"counterpart to PPAD ∩ PLS and contains many interesting problems - is itself equal to PPAD ∩ PLS.

Item Type: Conference or Workshop Item (Unspecified)
Additional Information: Updated based on reviewer comments, including a non-computer-assisted proof
Uncontrolled Keywords: TFNP, computational complexity, continuous optimization
Depositing User: Symplectic Admin
Date Deposited: 11 Nov 2020 11:25
Last Modified: 23 Feb 2023 21:07
DOI: 10.1145/3568163
Related URLs:
URI: https://livrepository.liverpool.ac.uk/id/eprint/3106588

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