Planck's law In 1880, André-Prosper-Paul Crova published a diagram of the three-dimensional appearance of the graph of the strength of thermal radiation as a function of wavelength and temperature. He determined the spectral variable by use of prisms. He analyzed the surface through what he called "isothermal" curves, sections for a single temperature, with a spectral variable on the abscissa and a power variable on the ordinate. He put smooth curves through his experimental data points. They had one peak at a spectral value characteristic for the temperature, and fell either side of it towards the horizontal axis. Such spectral sections are
Graph minor apply this result constructively, it is necessary to know what the forbidden minors of the graph family are. In some cases, the forbidden minors are known, or can be computed. In the case where "H" is a fixed planar graph, then we can test in linear time in an input graph "G" whether "H" is a minor of "G". In cases where "H" is not fixed, faster algorithms are known in the case where "G" is planar. Graph minor In graph theory, an undirected graph "H" is called a minor of the graph "G" if "H" can be formed from