Convergence Properties of Certain Minres Algorithms.
Levin (1988) has challenged the convergence properties of the Harman and Jones (1966) method of Minres factor analysis. Levin claimed that convergence of the Harman and Jones method is not guaranteed and that a modified version of this method, with proven convergence, is to be preferred. In the present article it is shown that both claims are invalid. Monotone convergence of the Harman and Jones method is guaranteed whereas the modified version, proposed by Levin, may converge to an incorrect solution. Levin has also claimed that the rank-one version of the Harman and Jones method, as implemented in a method by Zegers and ten Berge (1983) lacks a valid convergence proof, and that a method suggested by Comrey and Ahumada (1964, 1965) should be used instead. It is shown that these claims, too, should be reversed.
Note on Convergence of Minres.
Minres is an interactive least-squares factor, analytic procedure that minimizes the sum-of-squares of the off-diagonal residuals of the correlation matrix. The procedure solves successively for the rows (or the elements of the columns) of the factor pattern. Some versions of Minres proceed by replacing the solved row back into the pattern immediately after each step, but these procedures do not guarantee convergence. Application of the alternating least-squares procedure is recommended. The original solution by Comrey and Ahumada (1964) is correct.
The Globalization problem for inner automorphisms and Skolem-Noether theorems
We investigate the circumstances under which an inner automorphism of a ring with local units can be built from “local” information. Specifically, we consider three natural “inner” type properties for an automorphism of a ring with local units. We show that every inner automorphism is locally inner but the converse is false, even if the automorphism is “piecewise” inner. On the other hand, we construct a large class of rings for which every locally inner automorphism is actually inner. Finally we obtain some Skolem-Noether type Theorems for infinite matrix and triangular matrix rings.