# Questions tagged [induction]

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### Generalizations of classical tiling problem

A classic problem using an inductive construction is to show that the $2^n \times 2^n$-square, with a missing corner, can be tiled with L-triominoes. The proof goes like this: It is true for $n=1$, ...
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### Limit of alternated row and column normalizations

Let $E_0$ be a matrix with non-negative entries. Given $E_n$, we apply the following two operations in sequence to produce $E_{n+1}$. A. Divide every entry by the sum of all entries in its column (...
132 views

### Models of arithmetical theory R + induction in which successor is not injective

Consider the arithmetical theory sometimes denoted by $\mathsf{R}$. The non-logical vocabulary of $\mathsf{R}$ consists of '$0$', '$S$', '$+$' and '$\times$'. The axioms of this theory are all true ...
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### Proving the existence of a sequence with recursive growth constraints

Fix $0 < c < 1/3$. Show that there exists a strictly increasing sequence $a_k > 0$, a sequence $b_k \geq 0$, and an infinite set $K \subseteq \mathbb{Z}_{>0}$ such that \begin{align}\...
511 views

### Mathematical induction vis-a-vis primes

One of the most used proof-techniques is mathematical induction, and one of the oldest subjects is the study of prime numbers. Thanks to Euclid, we can consider the primes as a infinite monotone ...
398 views

### Inductive Definitions in Category Theory

I'm trying to pin down a notion of inductive definability in category-theoretic terms. The sorts of inductively defined sets (and classes) I'm most interested in are those that admit of induction and ...
394 views

### When must one strengthen one's induction hypothesis?

My questions are about the phenomenon that in order to prove a fact $\forall x \phi(x)$ by induction, sometimes straightforward induction "does not work" and instead one "must" use a "stronger" ...
2k views

### Is Cauchy induction used for proofs other than for AM–GM?

The proof by Cauchy induction of the arithmetic/geometric-mean inequality is well known. I am looking for a further theorem whose proof is much neater by this method than otherwise.
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### Affine analog of the theory of sheets

In the study of adjoint orbits in a complex semi-simple lie algebra, there is a well known object known as a "sheet". These are the irreducible components of the union of orbits of the same dimension. ...
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### Problem with a proof in Wellfounded trees in categories

I'm reading the paper Wellfounded trees in categories by Moerdijk and Palmgren. I'm having trouble understanding the proof of Theorem 7.2 (page 216), i.e. that in $\mathbf{ML}_{< \omega} \mathbf{W}$...
62 views