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The general idea behind trust region methods is known by many names; the earliest use of the term seems to be by Sorensen (1982). [1] A popular textbook by Fletcher (1980) calls these algorithms restricted-step methods . [ 2 ]
LMA can also be viewed as Gauss–Newton using a trust region approach. The algorithm was first published in 1944 by Kenneth Levenberg , [ 1 ] while working at the Frankford Army Arsenal . It was rediscovered in 1963 by Donald Marquardt , [ 2 ] who worked as a statistician at DuPont , and independently by Girard, [ 3 ] Wynne [ 4 ] and Morrison.
If the Cauchy point is inside the trust region, the new solution is taken at the intersection between the trust region boundary and the line joining the Cauchy point and the Gauss-Newton step (dog leg step). [2] The name of the method derives from the resemblance between the construction of the dog leg step and the shape of a dogleg hole in ...
The predecessor to PPO, Trust Region Policy Optimization (TRPO), was published in 2015. It addressed the instability issue of another algorithm, the Deep Q-Network (DQN), by using the trust region method to limit the KL divergence between the old and new policies.
Trust Region Policy Optimization (TRPO) is a policy gradient method that extends the natural policy gradient approach by enforcing a trust region constraint on policy updates. [6] Developed by Schulman et al. in 2015, TRPO ensures stable policy improvements by limiting the KL divergence between successive policies, addressing key challenges in ...
The Symmetric Rank 1 (SR1) method is a quasi-Newton method to update ... Because of the limited-memory matrix, the trust-region L-SR1 algorithm scales linearly with ...
However, some real-life applications (like Sequential Quadratic Programming methods) routinely produce negative or nearly-zero curvatures. This can occur when optimizing a nonconvex target or when employing a trust-region approach instead of a line search. It is also possible to produce spurious values due to noise in the target.
Localized molecular orbitals are molecular orbitals which are concentrated in a limited spatial region of a molecule, such as a specific bond or lone pair on a specific atom. They can be used to relate molecular orbital calculations to simple bonding theories, and also to speed up post-Hartree–Fock electronic structure calculations by taking ...