Examples of using Second-order arithmetic in English and their translations into Portuguese
{-}
-
Colloquial
-
Official
-
Medicine
-
Financial
-
Ecclesiastic
-
Ecclesiastic
-
Computer
-
Official/political
Finally, we prove the equiconsistency between these theories and peano second-order arithmetic.
Over ACA0, each formula of second-order arithmetic is equivalent to a Σ1n or Π1n formula for all large enough n.
It has close connections with definability in second-order arithmetic and with weak systems of set theory such as Kripke-Platek set theory.
Suppose that L is the language of Peano arithmetic the language of second-order arithmetic or arithmetic in all finite types would work as well.
In this case, Kőnig's lemma is provable in second-order arithmetic with arithmetical comprehension,
Reverse mathematics===The program of"reverse mathematics" asks which set-existence axioms are necessary to prove particular theorems of mathematics in subsystems of second-order arithmetic.
The first-order functions that are provably total in second-order arithmetic are precisely the same as those representable in system F Girard and Taylor 1987, pp. 122-123.
Second-order arithmetic can also be seen as a weak version of set theory in which every element is either a natural number
The formal theory of second-order arithmetic(in the language of second-order arithmetic) consists of the basic axioms,
Baire space because they fit with the language of ordinary second-order arithmetic.
is called the intended or standard model of second-order arithmetic.
can be proved in the stronger system of second-order arithmetic.
it is possible to formalize the real numbers in second-order arithmetic.
can be proven in the larger system of second-order arithmetic.
of the analytical hierarchy if it is definable by a formula of second-order arithmetic with only universal set quantifiers and no other set quantifiers.
There are weak fragments of second-order arithmetic called RCA* 0
every formula in the language of second-order arithmetic is Σ n 1{\displaystyle\Sigma_{n}^{1}}
is classified at level Σ 1 1{\displaystyle\Sigma_{1}^{1}} of this hierarchy if it is definable by a formula of second-order arithmetic with only existential set quantifiers and no other set quantifiers.
can be proven to be true in the larger system of second-order arithmetic.
The analytical hierarchy of formulas includes formulas in the language of second-order arithmetic, which can have quantifiers over both the set of natural numbers,