Research

Optimal transport / efficient attention / ML systems

Research where mathematical structure meets hardware constraints.

I work on learning systems that have to survive both theoretical scrutiny and real machines: differentiable transport, long-context attention, sparse derivatives, and implementations designed around the memory hierarchy.

Featured paper · Accepted at NeurIPS 2026 · arXiv:2605.08123

Block-Wise Differentiable Sinkhorn Attention

Tail-refinement gradients with a gap-aware dustbin bridge: a memory-efficient route to differentiating balanced entropic optimal-transport attention at long context.

Block-wise transport attention

The active tile moves through banded support while the rest of the plan stays out of memory.

Your browser does not support Canvas. The paper uses a streamed block-wise transport schedule with one resident reference plan tile.

01 · Exact surrogate adjoint

One reference tile

For the reported two-step refinement path, the four staircase plan factors can be reconstructed from one resident reference tile and explicit row and column modifiers.

02 · Hardware-aware schedule

Stream the active support

Fixed-width block-wise execution yields O((T+R)LW) work, O(Ld) input storage, and O(L) additional HBM for fixed head dimension and band width.

03 · Structured gaps

Dustbin augmentation bridge

The implemented gap-aware path is formalized as the same balanced surrogate on an augmented support, allowing the adjoint schedule to lift without claiming a general unbalanced model.

Transport topology · Preprint · September 2026

Support Topology and Gradient Mixing in Sinkhorn Layers

How does a sparse transport graph shape the gradients that pass through it? A fixed-support calculus connects Sinkhorn differentiation to two-step walks, overlap, and contraction.

From support to gradient mixing

Local overlap can spread a signal without guaranteeing contraction in one cycle.

A two-step walk through a transport support Follow a column through its incident rows to the columns they share. Choose a support above to compare the paths.
Column → row → column. Highlighted paths start at column 1.

Homogeneous cotangent

Watch a difference spread.

Start with +1 and −1 on opposite columns. Each cycle applies Mᵀ to that zero-sum signal.

Cycle 0 Remaining TV 100%

Dashed outlines mark the starting signal. Bars keep the same scale.

One-step coefficient τ(M) = 1.00

01 · Derivative structure

A walk behind the gradient

Each normalization cycle induces a stochastic operator on column-potential perturbations modulo constants. Its transpose carries zero-mass reverse-mode signals.

02 · Uniform guarantees

Every feasible face matters

At balanced plans, score-uniform one-step contraction requires pairwise two-hop column overlap on every feasible face of the transportation polytope.

03 · Sparse schedules

Mixing across several steps

Ordered support schedules can provide contraction over a window even when an individual layer has no global one-step guarantee.

Publications

Research record

Work on efficient transport attention and the support geometry that governs its gradients.

2026

Preprint

Support Topology and Gradient Mixing in Sinkhorn Layers

Dylan Forde

2026

Accepted at NeurIPS

Block-Wise Differentiable Sinkhorn Attention: Tail-Refinement Gradients with a Gap-Aware Dustbin Bridge

Dylan Forde

Earlier research threads

Problems that shaped the current work

Deep reinforcement learning

Intrinsic quantification of domain shift

Reactive exploration methods for measuring domain-shift magnitude across controlled reinforcement-learning environments.

Computational biology

Multi-omics and biological representation learning

Research across biomarker discovery, protein representations, regulatory networks, and learning from heterogeneous biological signals.

Medical imaging

Attention across volumetric MRI

Patch tokenization, self-attention, and inter-slice aggregation for volume-aware diagnostic classification.