Pyrolysis–gas chromatography–mass spectrometry is an analytical technique in which samples (typically polymeric) are rapidly thermally decomposed to produce smaller fragment molecules. These fragments are sent through a gas chromatograph which separates them into groups which have the same composition. Each group of fragments are then detected by a mass spectrometer that further fragments each molecule and measures the abundance and mass of each fragment. Because scientists understand the ways that molecules break up into fragments, an artificial intelligence computer program can reconstruct and identify the structure of each fragment that entered the mass spectrometer. So, this technique can infer the structure of the original mixture in the sample.