Is Minimum Canonical cover supposed to be singular? Is Minimum Canonical cover supposed to be singular?

For example when I calculate Fc for:

AC-&gt;BD
B-&gt;ACD


I get different results if I remove AC-&gt;D before B-&gt;D and vice versa, so can there be many covers?
In general different results can be produced, depending on the order in which the dependencies are considered for the elimination of extraneous attributes and redundant dependencies. This means that even the normalization algorithms, like the analysis algorithm for BCNF, can produce different results in certain cases.

A terminological note: in general the algorithms used for the normalization start by computing any canonical cover. A minimal canonical cover is a cover which has a number of dependencies less than that of equivalent covers. An optimal canonical cover is a cover that has less symbols of attributes than each other set equivalent to it. Different algorithms exists for the different type of covers, some of them are discussed in Maier, D. The Theory of Relational Databases, Computer Science Press, Rockville, Maryland, 1983.