[r-t] Proofs, etc

[Mark Davies]

Richard writes,

> Certainly when I've written computer programs to search for
> compositions, I've usually written them in terms of false lead heads
> rather than the incidence of course falseness.

More precisely, machine search should use falseness between nodes, where a
node is a subdivision of a course which cannot be interrupted by calls. For
tenors-split searches, a node may be a lead. For tenors-together searches,
nodes can be longer than one lead, e.g. M to B in London. For certain
searches, a node may be less than a lead, for example in Stedman, or in a
half-lead-spliced search where compositing of half-leads is not performed.

Graham writes,

> But in that case FCHs are ... mutual transpositions of a closed group
> (namely the 7 leadheads of a plain course).

I expect this is a coset in proper talk. ;-D

MBD