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22

part of the graph including every part that
will be affected by the operation and only
operate upon the new replica so produced.

Operation A Two oddly enclosed lines of
identity on the same area may be joined;
and an evenly enclosed line of identity may be severed.
These operations are irreversible.

Operation B. From any line of identity lying
just outside a cut a branch may be made extending
into the cut; and this operation is reversible.

Operation C. A disconnected line of identity ligature
can anywhere be scribed or erased.

But what is generally useful is to iterate an
evenly enclosed partial graph within an even
number of additional cuts,
or an oddly enclosed partial graph within an odd number of additional cuts,
to extend a branch from an evenly enclosed line of identity into an