Defining left behind places: an internationally comparative poset analysis.

This article focuses on defining and evaluating "left-behind" places in Europe through a pluralistic framework grounded in Amartya Sen's Capability Approach and the "leaving no one behind" (LNOB) principle. It critiques existing composite indicators for oversimplifying or fragmenting multidimensional regional inequalities and proposes the use of partially ordered sets (posets) and Hasse diagrams to capture incomparabilities among diverse indicators across 451 NUTS 2 regions. The study identifies five classes of approaches—ranging from narrow economic measures to broader social, political, and subjective dimensions—and demonstrates that different indicators yield distinct regional rankings, revealing multiple "structures of left-behindness" rather than a single uniform pattern. Sensitivity analyses show that economic variables often dominate rankings but that other dimensions, including political discontent and health, significantly influence the characterization of left-behind regions, underscoring the need for context-specific, integrated policy responses rather than one-size-fits-all solutions.