The Louvre Theft, and the Solution

By Minjong Sung

The 19th of October 2025 was a hectic day for antique collectors, French police, and security guards at the Louvre. At 9:30 am, 30 minutes after the museum opened to visitors, thieves disguised as construction workers broke into the museum and stole eight pieces of the French Crown Jewels. After a week of tireless manhunt, the French police announced the comprehension of the suspects on 29th October. The robbery shocked many, as it was the first time the world’s renowned museum had been dared to be robbed since 1998.

There is no doubt that the modern security system is complex and has developed to its sophistication for decades. But one cannot deny that it failed to stop the crime completely. Could a solution to a 50-year-old mathematical problem provide a remedy to the Louvre’s security plans?

The art gallery problem poses the question, “What is the minimum number of guards needed to observe the whole gallery?” The layout of the gallery is represented as a polygon, a straight-sided plane figure with at least three sides and angles. Guards, represented by dots, can be placed anywhere on or inside the polygon. They must stay in fixed positions, but they are able to rotate freely (think of 360 vision). A point of the gallery is considered visible if a straight line can be drawn from the guards to a point on the wall of the polygon.

In 1975, mathematician Václav Chvátal proposed a groundbreaking theorem: any simple polygon with n vertices can be fully monitored with [n/3] guards. This result, later proven rigorously, provided a concrete upper bound for the old question of optimal surveillance.

The significance of Chvátal’s theorem extends well beyond theoretical mathematics. By triangulating the polygon—dividing it into non-overlapping triangles—one can identify a set of strategic vertices such that a guard positioned at each ensures visibility of every region in the space. Although it does not always guarantee the minimum number of guards, it guarantees a number that will always work, giving law enforcement and engineers a functional formula for designing surveillance layouts.

Still, the elegance of the theorem also reveals its limitation when applied to real-world spaces like the Louvre. Museum galleries rarely form ideal polygons; they twist, widen, narrow, and incorporate hallways, alcoves, display cases, and multiple floors. Real walls are not abstract line segments but contain pillars, reflective surfaces, and visual obstructions. In other words, a museum is not a polygon—at least, not a simple one.

Yet the underlying idea remains powerful: by reducing a complex space into geometric components, one can analyze its blind spots more systematically. Even an imperfect polygonal approximation of a gallery can highlight zones that require additional guards or cameras. In this sense, Chvátal’s work becomes less a precise instruction manual and more a conceptual tool—a mathematical lens through which modern security planners can diagnose weaknesses before criminals exploit them.