Basic results on Filter.atTop and Filter.atBot filters #
In this file we prove many lemmas like “if f → +∞, then f ± c → +∞”.
Alias of the forward direction of Filter.eventually_atTop.
Sequences #
A function f maps upwards closed sets (atTop sets) to upwards closed sets when it is a
Galois insertion. The Galois "insertion" and "connection" is weakened to only require it to be an
insertion and a connection above b.
A function f maps downwards closed sets (atBot sets) to downwards closed sets when it is a
Galois coinsertion. The Galois "coinsertion" and "connection" is weakened to only require it to be
an insertion and a connection below b.
A function f maps upwards closed sets (atTop sets) to upwards closed sets when it is a
Galois insertion. The Galois "insertion" and "connection" is weakened to only require it to be an
insertion and a connection above b.
A function f maps downwards closed sets (atBot sets) to downwards closed sets when it is a
Galois coinsertion. The Galois "coinsertion" and "connection" is weakened to only require it to be
an insertion and a connection below b.
The image of the filter atTop on Ici a under the coercion equals atTop.
The image of the filter atBot on Iic a under the coercion equals atBot.
The image of the filter atTop on Ioi a under the coercion equals atTop.
The image of the filter atBot on Iio a under the coercion equals atBot.
The atTop filter for ↑(Ioi a) comes from the atTop filter in the ambient order.
The atBot filter for ↑(Iio a) comes from the atBot filter in the ambient order.
The atTop filter for ↑(Ici a) comes from the atTop filter in the ambient order.
The atBot filter for ↑(Iic a) comes from the atBot filter in the ambient order.