Therefore, By Induction
par CUMULUS
Experimental

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par CUMULUS
Experimental

Écoute ce morceau sur la radio communautaire Anthem.
Ouvrir sur Anthem · Page de l'artiste · Album : The Flop Ten
Step one. Establish the base case.
Let n equal one, and verify by hand.
The left side reads one.
The right side reads one times two over two.
One equals one.
The base case holds.
(Definition: P of n, a statement indexed by n)
(for every n in the natural numbers)
(Definition: the well-ordering principle)
(every non-empty subset has a least element)
Therefore, by induction.
Therefore, by induction.
For all n.
For all n.
Therefore, by induction.
Step two. Assume the inductive hypothesis.
Suppose P of k holds for one fixed k.
We do not prove k.
We are permitted to assume it.
The assumption is discharged at the end.
This is the method.
(Reference: Peano, axiom five)
(Contra-indication: do not assume P of every k)
(Reference: the principle of strong induction)
(permitted only where stated)
Add k plus one to both sides.
Factor. Collect the terms.
The expression becomes
k plus one, times k plus two, over two.
Which is the statement P of k plus one.
The implication holds.
Therefore, by induction.
Therefore, by induction.
For all n.
For all n.
Therefore, by induction.
Step three. The inductive step is closed.
P of one is true.
P of k implies P of k plus one.
The set of n for which P fails
has no least element.
Therefore the set is empty.
(The indicator moves from red to green)
(File in triplicate: base, hypothesis, step)
(The bubble rests between the lines)
(Dust lifted on the finger: none)
Therefore, by induction.
Therefore, by induction.
Therefore, by induction.
For all n. For all n.
Quod erat demonstrandum.
Therefore, by induction.
Therefore, by induction.
For all n in the natural numbers.
For all n.
For all n.
Therefore, by induction.
No further cases remain.
The proof is closed.