[math-fun] There's one side to every story

We like to say that a Moebius strip embedded in 3-space has one side, whereas a unit disk there has two. How can we say that? What are the "sides" of a 2-dimensional set of points? It is its own boundary. --rwg ESPACEMENT ESCAPEMENT INTERSPACE ESTRAPENIC PARENETICS TRIPLE SPACE TEA CLIPPERS SPENCERIAN INNER SPACE PERNANCIES LATTICE SPACE ACCEPTILATES OPEN STANCES TENONS SPACE HILBERT SPACE PEACH BLISTER LINE SPACER PERCALINES PLAINS CREE PERICLEANS