metalogic and set theory Flashcards
the study of logical systems
metalogic
any argument we can formally prove is valid
soundness
we can formally prove any tautologically valid argument
- if an argument is formally provable in BOOL, then the argument is valid
completeness
true or false: if a conclusion, C, is provable in a formal proof from some premises, then those premises entail C.
true
the ability to express any possible truth function
truth function completeness (not the same as completeness)
what are the things in the set?
elements or members
true or false: sets can have other sets as elements
true
set builder notation
{Ax: x is prime}
set member relation
weird E
how do you say “a is a member of b”?
a E b
3 rules of sets
- order doesn’t matter
- repetition doesn’t matter
- name choice doesn’t matter
how do you represent the empty set?
{} or /O
number of elements in the set
cardinality
|a|
|N|
infinite number aleph naught