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had to look that up Retarded differential equations (RDEs) are differential equations having retarded arguments. https://www.sciencedirect.com/science/article

had to look that up Retarded differential equations (RDEs) are differential equations having retarded arguments. https://www.sciencedirect.com/science/article/pii/S0377042700004763 https://www.sciencedirect.com/science/article/pii/S037704270...

MikeDelta 5y ago
And quantum physics has degenerate energy levels. https://en.wikipedia.org/wiki/Degenerate_energy_levels https://en.wikipedia.org/wiki/Degenerate_energy_levels