Is there a IsDefinedQ function?
36954
What does the construct f[x_] := f[x] = ... mean?
36989
Determining functions from specifications...
119129
Determining whether there is a short exact sequence
66359
Get the actual query executed by a view
74483
Correct way to detect sequence parameter?
104986
Does AES have any fixed-points?
35434
Check if $REPLY is in a range of numbers
26620
#ifdef #ifndef in Java
576
How can I check for an empty/undefined/null string in JavaScript?
15853
Is there a way to see a prepared query as it will be executed on the database?
55996
How can I know if a node is already defined?
99415
Implementing a safe ValueQ that does not evaluate its argument
116330
What is the best way to check whether lead belongs to Queue or User?
50420
How to tell if an IEnumerable is subject to deferred execution?
61489
Is there a statement whose undecidability is undecidable?
68416
Determine where a function was executed?
103788
checking for equality on dispatch_queue_t