underfilter

Definitions

1. A morphological filter (idempotent operator) whose image is a subset of the domain.
2. A filter that is positioned beneath something.

Examples

“It is clear that overfilters and underfilters are dual in the sense⟳ of the duality principle.”

“The paving downstream consisted of 18x18x8-inch blocks laid on edge over a brick base⟳ which in turn⟳ was underlain with a gravel or brick chip filter. Since there was some controversy as to whether an underfilter was necessary, the first test⟳ was made with the filter omited.^([sic])”

“Since there is no underfilter, the top flow⟳ line emerges on the downstream slope.”

“A single sheet of filter paper is used as an underfilter.”

“In addition, the flow⟳ from the underfilter, which had previously been clear, became cloudy, indicating that the filter had failed to block⟳ particles from the core.”

CEFR level