# Logica

Funzione inversa. Da Wikipedia, l'enciclopedia libera. manda 3 in a poiché f manda a in 3 si dice invertibile se esiste una funzione.

Omomorfismo. Da Wikipedia, l'enciclopedia libera. è un omomorfismo se vale per ogni coppia di elementi di , dove e.

König's lemma. König's lemma or König's infinity lemma is a theorem in graph theory due to Dénes Kőnig (1936).[1] It gives a sufficient condition for an infinite graph to have an infinitely long path.

The computability aspects of this theorem have been thoroughly investigated by researchers in mathematical logic, especially in computability theory. This theorem also has important roles in constructive mathematics and proof theory. Statement of the lemma Note that the vertex degrees must be finite, but need not be uniformly bounded: it is possible to have one vertex of degree 10, another of degree 100, a third of degree 1000, and so on.

Proof Modal Logic. First published Tue Feb 29, 2000; substantive revision Fri Oct 2, 2009 A modal is an expression (like ‘necessarily’ or ‘possibly’) that is used to qualify the truth of a judgement.

Modal logic is, strictly speaking, the study of the deductive behavior of the expressions ‘it is necessary that’ and ‘it is possible that’. Some paradoxes - an anthology. Richard's Paradox. Here are three paradoxes, all based on the same idea. 1.

Let A be the set of all positive integers that can be defined in under 100 words. Since there are only finitely many of these, there must be a smallest positive integer n that does not belong to A. But haven't I just defined n in under 100 words? Non solo matematica... Funzione di Ackermann. Da Wikipedia, l'enciclopedia libera. oppure: La funzione di Ackermann è un esempio di funzione ricorsiva che non è primitiva ricorsiva poiché cresce più velocemente di qualsiasi funzione ricorsiva primitiva.

(mediante iterazione di.