Physiocracy is perhaps the first well-developed theory of economics.
Because linear algebra is such a well-developed theory, nonlinear mathematical models are sometimes approximated by linear ones.
For one-dimensional kernels, there is a well-developed theory of multi-scale approaches, concerning filters that do not create new local extrema or new zero-crossings with increasing scales.
Lie groups form a very nice class of topological groups, and the compact Lie groups have a particularly well-developed theory.
For one-dimensional signals, there exists quite a well-developed theory for continuous and discrete kernels that guarantee that new local extrema or zero-crossings cannot be created by a convolution operation.
There is a well-developed theory for linear differential operators, due to Lars Gårding, in the context of microlocal analysis.
The British had their own very well-developed theory of strategic bombing, and built the long-range bombers to implement it.
Frobenius extensions have a well-developed theory of induced representations investigated in papers by Kasch and Pareigis, Nakayama and Tzuzuku in the 1950s and 1960s.
With dedicated facilities available on site, the Unit has particular strengths in the application of neuroimaging techniques in the context of well-developed neuro-cognitive theory.
Unlike these standards, Petri nets have an exact mathematical definition of their execution semantics, with a well-developed mathematical theory for process analysis.