22 Answers votes newest views recent 38What are some examples of ingenious, unexpected constructions? 1Fair but irregular polyhedral dice 3What is a continuous path? 2When a Banach space is a Hilbert space? 2What properties make $[0,1]$ a good candidate for defining fundamental groups? 3Topological Characterisation of the real line. 2How did “Ore’s Conjecture” become a conjecture? 1Reference for the Gelfand-Neumark theorem for commutative von Neumann algebras 2Direct construction of the integers 10Uncountable family of infinite subsets with pairwise finite intersections 4Is there an axiomatic approach of the notion of dimension ? 2Self-dual normed spaces which are not Hilbert spaces 5Orthogonality in non-inner product spaces 1Reformulation of amenability and growth rate of a group in terms of general metric spaces. 2Axiom of choice and convergence 1Ultrafilters and principal filters 2Representing a real number as the value of a countably infinite game 2Can we have a finite cyclic group of rational numbers (under multiplication)? 1A variational principle for amenable groups 1Invariant means on commutative magmas 3Why are Nash-Equilibria inside the Simplex S_n unique ? 5What is the domain of the “average operator”?