In his Elementary Treatise on Determinants, Dodgson
stated Jacobi’s Theorem as follows:
If there be a square Block of the nth degree, and if in it any
Minor of the mth degree be selected: the Determinant of the
corresponding Minor in the adjugate Block is equal...to the
product of the (m–1)th power of the Determinant of the first
Block, multiplied by the Determinant of the Minor
complemental to the one selected.
When m = 2, we get the following special case of the
theorem, which will help to clarify the mechanics of
Dodgson’s method of condensation:
Theorem (Jacobi): Let A be an n × n matrix. Consider the
2×2 minor consisting of