I vaguely recall that Soviet planners used something based on n-dimensional ellipsoids (instead of Simplex) to optimize resources allocations of Aereoflot fligh

I vaguely recall that Soviet planners used something based on n-dimensional ellipsoids (instead of Simplex) to optimize resources allocations of Aereoflot flights but I cannot remember anything more specific, alas. (I read this on the magazine of my country's equivalent of ACM in '80s and it somehow stuck with me all these years)