## Ultrasheaves and Double-Negation

2002-11-13T00:00:00Z (GMT) by
Moerdijk has introduced a topos of sheaves on a category of filters. Following his suggestion, we prove that its double negation subtopos is the topos of sheaves on the subcategory of ultrafilters - the <em> ultrasheaves. </em> We then use this result to establish a double negation translation of results between the topos of ultrasheaves and the topos on filters.