Skip to main content
Search type Search syntax
Tags [tag]
Exact "words here"
Author user:1234
user:me (yours)
Score score:3 (3+)
score:0 (none)
Answers answers:3 (3+)
answers:0 (none)
isaccepted:yes
hasaccepted:no
inquestion:1234
Views views:250
Code code:"if (foo != bar)"
Sections title:apples
body:"apples oranges"
URL url:"*.example.com"
Saves in:saves
Status closed:yes
duplicate:no
migrated:no
wiki:no
Types is:question
is:answer
Exclude -[tag]
-apples
For more details on advanced search visit our help page
Results tagged with
Search options not deleted user 8494

first-order and higher-order logic, model theory, set theory, proof theory, computability theory, formal languages, definability, interplay of syntax and semantics, constructive logic, intuitionism, philosophical logic, modal logic, completeness, Gödel incompleteness, decidability, undecidability, theories of truth, truth revision, consistency.

11 votes

Is all ordinary mathematics contained in high school mathematics?

Since Ackermann's function is not available in EFA, Tarjan's upper bound – the inverse Ackermann function – for the run-time of the union-find data structure is not provable in EFA. This probably does …
Greg Graviton's user avatar
0 votes

Construction of a maximal ideal

As Ashutosh points out, it's impossible to describe $M$ constructively. However, from a practical point view, the "untouchability" of ultrafilters and maximal ideals in $\mathcal C(\mathbb R)$is not …
Greg Graviton's user avatar
4 votes

An ultrafilter is a set of subsets containing exactly one element of each finite partition: ...

The alternate formulation is closely related to the following fundamental definition from Ramsey Theory Definition: Let $\phi : 2^X \to \lbrace\text{true},\text{false}\rbrace$ be a property pertainin …
Greg Graviton's user avatar