In "continuous" mathematics there are several important notions such as covering space, fibre bundle, Morse theory, simplicial complex, differential equation, real numbers, real projective plane, etc. that have a "discrete" analog: covering graph, graph bundle, discrete Morse theory, abstract simplicial complex, difference equation, finite field, finite projective plane, etc. I would like to know if there are others. But the real question is: Are there any important "continuous" mathematical concepts without discrete "discrete" analog and vice versa?

In "continuous" mathematics there are several important notions such as covering space, fibre bundle, Morse theory, simplicial complex, differential equation, real numbers, real projective plane, etc. that have a discrete "discrete" analog: covering graph, graph bundle, discrete Morse theory, abstract simplicial complex, difference equation, finite field, finite projecitve projective plane, etc. I would like to know if there are others. But the real question is: Are there any important mathematical concepts without discrete analog?

In mathematics there are several important notions such as covering space, fibre bundle, Morse theory, simplicial complex, differential equation, fieldreal numbers, projective plane, etc. that have a discrete analog: covering graph, graph bundle, discrete Morse theory, abstract simplicial complex, difference equation, finite field, finite projecitve plane, etc. I would like to know if there are others. But the real question is: Are there any important mathematical concepts without discrete analog?

In mathematics there are several important notions such as covering space, fibre bundle, Morse theory, simplicial complex, differential equation, field, projective plane, etc. that have a discrete analog: covering graph, graph bundle, discrete Morse theory, abstract simplicial complex, difference equation, finite field, finite projecitve plane, etc. I would like to know if there are others. But the real question is: Are there any important mathematical concepts without discrete analog?