4 papers
Unique expansion matroids and union minimal matroids
Hua Yao, William Zhu
The expansion axiom of matroids requires only the existence of some kind of independent sets, not the uniqueness of them. This causes that the base families of some matroids can be…
Applications of repeat degree on coverings of neighborhoods
Hua Yao, William Zhu
In covering based rough sets, the neighborhood of an element is the intersection of all the covering blocks containing the element. All the neighborhoods form a new covering called…
Condition for neighborhoods induced by a covering to be equal to the covering itself
Hua Yao, William Zhu
It is a meaningful issue that under what condition neighborhoods induced by a covering are equal to the covering itself. A necessary and sufficient condition for this issue has bee…
Condition for neighborhoods in covering based rough sets to form a partition
Hua Yao, William Zhu
Neighborhood is an important concept in covering based rough sets. That under what condition neighborhoods form a partition is a meaningful issue induced by this concept. Many scho…