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Ryan Pellico

Publications and source records attributed to Ryan Pellico.

5 recordsLinked to original sources

A Graph Laplacian Eigenvector-based Pre-training Method for Graph Neural Networks

The development of self-supervised graph pre-training methods is a crucial ingredient in recent efforts to design robust graph foundation models (GFMs). Structure-based pre-training methods are under-explored yet crucial for downstream applications which rely on underlying graph structure. In addition, pre-training traditional message passing GNNs to capture global and regional structure is often challenging due to the risk of oversmoothing as network depth increases. We address these gaps by proposing the Laplacian Eigenvector Learning Module (LELM), a novel pre-training module for graph neural networks (GNNs) based on predicting the low-frequency eigenvectors of the graph Laplacian. Moreover, LELM introduces a novel architecture that overcomes oversmoothing, allowing the GNN model to learn long-range interdependencies. Empirically, we show that models pre-trained via our framework outperform baseline models on downstream molecular property prediction tasks.

cs.LG

Well-hued graphs with first difference two

A graph $G$ is said to be well-hued if every maximal $k$-colorable subgraph of $G$ has the same order $a_k$. Therefore, if $G$ is well-hued, we can associate with $G$ a sequence $\{a_k\}$. Necessary and sufficient conditions were given as to when a sequence $\{a_k\}$ is realized by a well-hued graph. Further, it was conjectured there is only one connected well-hued graph with $a_2 = a_1 + 2$ for every $a_1 \ge 4$. In this paper, we prove this conjecture as well as characterize nearly all well-hued graphs with $a_1=2$. We also investigate when both $G$ and its complement are well-hued.

math.CO

Well-edge-dominated graphs containing triangles

A set of edges $F$ in a graph $G$ is an edge dominating set if every edge in $G$ is either in $F$ or shares a vertex with an edge in $F$. $G$ is said to be well-edge-dominated if all of its minimal edge dominating sets have the same cardinality. Recently it was shown that any triangle-free well-edge-dominated graph is either bipartite or in the set $\{C_5, C_7, C_7^*\}$ where $C_7^*$ is obtained from $C_7$ by adding a chord between any pair of vertices distance three apart. In this paper, we completely characterize all well-edge-dominated graphs containing exactly one triangle, of which there are two infinite families. We also prove that there are only eight well-edge-dominated outerplanar graphs, most of which contain at most one triangle.

math.CO

Modeling Magnetic Fields with Helical Solutions to Laplace's Equation

The series solution to Laplace's equation in a helical coordinate system is derived and refined using symmetry and chirality arguments. These functions and their more commonplace counterparts are used to model solenoidal magnetic fields via linear, multidimensional curve-fitting. A judicious choice of functional forms, a small number of free parameters and sparse input data can lead to highly accurate, fine-grained modeling of solenoidal magnetic fields, including helical features arising from the winding of the solenoid, with overall field accuracy at better than one part per million.

physics.ins-det

Random walks on barycentric subdivisions and the Strichartz hexacarpet

We investigate the relation between simple random walks on repeated barycentric subdivisions of a triangle and a self-similar fractal, Strichartz hexacarpet, which we introduce. We explore a graph approximation to the hexacarpet in order to establish a graph isomorphism between the hexacarpet approximations and Barycentric subdivisions of the triangle, and discuss various numerical calculations performed on the these graphs. We prove that equilateral barycentric subdivisions converge to a self-similar geodesic metric space of dimension log(6)/log(2), or about 2.58. Our numerical experiments give evidence to a conjecture that the simple random walks on the equilateral barycentric subdivisions converge to a continuous diffusion process on the Strichartz hexacarpet corresponding to a different spectral dimension (estimated numerically to be about 1.74).

math.MG