57

44

those of the alpha cut.

Rules of the Broken Cut

Rule 1. In a broken cut already on the
sheet of assertion any graph may be inserted.

Rule 2. An evenly enclosed alpha cut may be
half erased so as to convert it into a broken
cut, and an oddly enclosed broken cut may
be filled up to make an alpha cut.
Whether the enclosures are by alpha or broken cuts is indifferent.

Consequently
[diagram: g enclosed in broken enclosed in alpha cut]
will mean that the graph g is beta-necessarily
true. By Rule 2, this is converted into
[diagram]
which is equivalent to
g