4 papers
Transpose-free linear algebra
Diana Halikias, Michiel E. Hochstenbach, Alex Townsend
We study the limitations of matrix-free algorithms that access a matrix only through forward matrix-vector products (matvecs) , without access to the transpose $A…
Oblivious Subspace Injection Is Not Enough for Relative Error
Alex Townsend, Chris Wang
Oblivious subspace injection (OSI) was introduced by Camaño, Epperly, Meyer, and Tropp in 2025 as a much weaker sketching property than oblivious subspace embedding (OSE) that stil…
Beyond singular value gaps in randomized subspace approximation
Christopher Wang, Alex Townsend
The success of randomized range finders (RRFs) is typically analyzed via the singular value gaps of a target matrix . In this work, we show that the so-called Frobenius singular…
Operator learning without the adjoint
Nicolas Boullé, Diana Halikias, Samuel E. Otto +1
There is a mystery at the heart of operator learning: how can one recover a non-self-adjoint operator from data without probing the adjoint? Current practical approaches suggest th…