Does any branch of mathematics concern exclusively the dissimilarity of patterns?
I'm not entirely sure what that means. Ramsey Theory studies the inevitability of patterns, but that's different...
Considering that math concerns the similarity of patterns, I guess that dissimilarity is a pattern unto itself.
Indeed, this is one of the reasons I believe Mathematics is so applicable to everything. If something has some pattern, we use maths to study it. If it doesn't have a pattern, we call it random and do statistical analysis on that. However something turns out, we have maths for it!
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