Or better, one’s idea of what constitutes a “reasonable-sounding statement” in the first place changes, to better accommodate what is actually true.
(Checking those examples is good; but even better would be not to need to, due to having an appropriate feeling for how abstract a topological space is.)
Completely agreed. Part of this might look like a shift in definitions/vocabulary over time. Coming to topology from analysis, sequence felt like a natural way to interrogate limiting behavior. After a while though, it sort of became clear that thinking sequentially requires putting first-countability assumptions everywhere. Introducing nets did away with the need for this assumption and better captured what convergence ought to mean in a general topological spaces.
Or better, one’s idea of what constitutes a “reasonable-sounding statement” in the first place changes, to better accommodate what is actually true.
(Checking those examples is good; but even better would be not to need to, due to having an appropriate feeling for how abstract a topological space is.)
Completely agreed. Part of this might look like a shift in definitions/vocabulary over time. Coming to topology from analysis, sequence felt like a natural way to interrogate limiting behavior. After a while though, it sort of became clear that thinking sequentially requires putting first-countability assumptions everywhere. Introducing nets did away with the need for this assumption and better captured what convergence ought to mean in a general topological spaces.