Chemistry

Lewis-labeled graphs: curly arrows and fishhooks as executable electron transfers

Tieu-Long Phan

Featured August 7, 2026

AI-generated analysis — This is SciGrove's AI interpretation of the paper, not peer-reviewed content. Always refer to the original paper.

Simply

A new way to draw molecules, called Lewis-labeled graphs, makes sure that when chemists draw curly arrows to show how electrons move in a reaction, the computer can actually check if those electrons are really there and if the reaction makes sense.

In depth

This paper introduces the Lewis-labeled graph (LLG), a molecular representation that explicitly encodes lone pairs, radical electrons, and separates sigma (

s i g ma

) and pi (

p i

) bond occupancies directly into atom and bond labels. This allows for resource-constrained double-pushout (DPO) rewriting rules to verify electron availability before executing chemical transformations, aligning molecular states, reaction rules, and electron-flow annotations into a single, verifiable framework.

Key Takeaways

1
The Lewis-labeled graph (LLG) explicitly encodes electron resources (lone pairs, radicals, $s i g ma$ / $p i$ bonds) into atom and bond labels, enabling rigorous electron accounting.
2
Chemical transformations are formalized as resource-constrained double-pushout (DPO) rules that verify electron availability against a common pre-state, preventing chemically impossible matches.
3
The framework establishes three-level coherence, proving that electron-flow annotations, induced DPO rules, and integral occupancy updates are equivalent, ensuring deterministic and auditable reaction execution.

Conceptual Flow

HIGH LEVEL

Methodology: How Electron Flow Becomes Executable

The paper makes electron movements in chemistry understandable by computers, by adding electron details to molecule drawings and checking if the electron changes make sense.

Old Molecule Drawing

Electron Movement Arrows

Add Electron Details

New Molecule Drawing

Check Electron Rules

Results: More Accurate Reaction Predictions

By checking electron rules, the new method avoids wrong reaction predictions that old methods made, leading to fewer incorrect outcomes.

Old Method Predictions

New Method Predictions

Compare Outcomes

Fewer Wrong Reactions

All Correct Reactions

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