The reason each line is assumed to contain at least 3 points is to eliminate some degenerate cases.

If the degree is less than 2, this may be called a "degenerate case".

The circle would be regarded as a degenerate case.

The degenerate case of this construction is the empty language, which contains no words at all ().

The degenerate case of a foil is a simple flat plate.

The last condition excludes the so-called degenerate cases (see below).

An enumerated type can be seen as a degenerate case: a tagged union of unit types.

This formula will not work for degenerate cases (when the polynomial factors).

In the degenerate case when the line element in the interaction region takes the form.

In particular authors often did not bother to check degenerate cases.