# HG changeset patch # User wenzelm # Date 1515773674 -3600 # Node ID 060efe5321898ae789b0fb9e699beab037d25bec # Parent 4a4c14b2480084ad4f0da12450548822d67030b9 prefer formal text; diff -r 4a4c14b24800 -r 060efe532189 src/HOL/Library/Going_To_Filter.thy --- a/src/HOL/Library/Going_To_Filter.thy Fri Jan 12 15:27:46 2018 +0100 +++ b/src/HOL/Library/Going_To_Filter.thy Fri Jan 12 17:14:34 2018 +0100 @@ -4,7 +4,9 @@ A filter describing the points x such that f(x) tends to some other filter. *) -section \The `going\_to' filter\ + +section \The \going_to\ filter\ + theory Going_To_Filter imports Complex_Main begin @@ -18,7 +20,7 @@ where "f going_to F \ f going_to F within UNIV" text \ - The `going\_to' filter is, in a sense, the opposite of @{term filtermap}. + The \going_to\ filter is, in a sense, the opposite of @{term filtermap}. It corresponds to the intuition of, given a function $f: A \to B$ and a filter $F$ on the range of $B$, looking at such values of $x$ that $f(x)$ approaches $F$. This can be written as @{term "f going_to F"}. @@ -27,7 +29,7 @@ of infinity (i.\,e.\ all values sufficiently far away from the zero). This can also be written as @{term "norm going_to at_top"}. - Additionally, the `going\_to' filter can be restricted with an optional `within' parameter. + Additionally, the \going_to\ filter can be restricted with an optional `within' parameter. For instance, if one would would want to consider the filter of complex numbers near infinity that do not lie on the negative real line, one could write @{term "norm going_to at_top within - complex_of_real ` {..0}"}.