Before a stick of deodorant reaches a consumer's bathroom counter, it moves through a complex supply chain. Raw materials and packaging components are sourced, assembled into a finished product, and shipped through warehouses and distribution centers before finally reaching a store shelf. 
 

At each step, companies must decide how much extra inventory to keep. A product can be available, in stock, and ready to ship, yet still be out of reach when customers need it most. In today's interconnected supply chains, even a small disruption can cascade across networks, leading to empty shelves or production delays.
 

“Companies can have plenty of inventory and still run out of products because they are in the wrong place,” explained Andre Calmon, associate professor of operations management at Georgia Tech’s Scheller College of Business. “Our research helps companies decide where to keep extra inventory so they can meet demand without tying up unnecessary money in products sitting on shelves.” 
 

Calmon and his co-authors, Philippe Blaettchen, Georgina Hall, and Mohit Tawarmalani received the 2026 INFORMS Computing Society Harvey J. Greenberg Research Award for their paper, “From Trees to Treewidth: Inventory Management in Complex Supply Chain Networks.” The award recognizes outstanding research at the intersection of operations research and computer science. 
 

A Faster Route to Better Inventory Decisions
 

For decades, major companies like Procter & Gamble, Intel, HP, and Boston Scientific have used a planning framework called the Guaranteed Service Model (GSM) to decide where inventory should be stored across a supply chain. The goal is simple: keep products available when customers need them while minimizing inventory costs.
 

Calmon and his co-authors developed a new mathematical method that makes those decisions much faster.
 

“Our main contribution is a fundamental theoretical advance,” Calmon said. “We developed the first exact method for the Guaranteed Service Model whose computing time is tied to a measure of network structure called treewidth.” 
 

While the underlying mathematics are complex, the core idea is surprisingly intuitive. Rather than analyzing an entire supply chain at once, the method breaks a large network into smaller, overlapping sections. Researchers can solve those sections more efficiently and then combine them into a single optimal plan. As a result, the structure of a supply chain can matter more than its overall size when determining how quickly the problem can be solved. 
 

The result is a dramatically faster way to identify the best inventory strategy.
 

In tests involving 38 real-world supply chains, the researchers found optimal inventory plans for every case they studied. Median computing time dropped from about nine-and-a-half minutes using the previous leading method to just 14 seconds. The new approach also solved large supply chain problems that existing methods could not complete.
 

For businesses, that speed could make it easier to prepare for disruptions before they happen.
 

“A company could test what happens if demand doubles in one region or if a supplier’s shipments take two weeks longer than expected,” Calmon said. “Because our method finds the best plan quickly, companies can explore more scenarios before a disruption and update their plans as conditions change.” 
 

That capability could be especially valuable during disruptive events like pandemics, natural disasters, geopolitical disruptions, or sudden changes in demand. By evaluating more possibilities in less time, companies may be able to maintain product availability while reducing excess inventory and waste. 
 

The Future of Supply Chain Research
 

Calmon's award-winning research grew from a question he once considered "unsolvable" as a doctoral student. Today, that same curiosity continues to guide his work. Looking ahead, he is particularly excited about applying his planning and optimization research to circular supply chains that recover, reuse, and recycle products and materials.
 

“When products and materials re-enter a supply chain, inventory planning becomes more complicated,” he said. “Helping companies manage those flows could make circular business models more practical.  I hope to help build planning tools that let companies tackle larger supply chains and test more possibilities at the speed their businesses require.” 

 
Read More: “Trees to Treewidth”
Learn More: Operations Management