<Verb>BoundaryPair(K):: RegCWComplex --> RegCWMap</Verb><P/>
<P/> Inputs a pure regular CW-complex <M>K</M> and returns the
regular CW-inclusion
map <M>\iota \colon \partial K \hookrightarrow
K</M> from the boundary
<M>\partial K</M> into the complex <M>K</M>.
