Minimally ramified deformations when

Decomposition types in minimally tamely ramified extensions of

When Shape Matters: Deformations of Tiling Spaces

We investigate the dynamics of tiling dynamical systems and their deformations. If two tiling systems have identical combinatorics, then the tiling spaces are homeomorphic, but their dynamical properties may differ. There is a natural map I from the parameter space of possible shapes of tiles to H of a model tiling space, with values in R. Two tiling spaces that have the same image under I are ...

Ramified Frege Arithmetic

Frege’s definitions of zero, predecession, and natural number will be explained below. As for second-order Dedekind-Peano arithmetic, the axiomatization most convenient for our purposes is the following: (1) N0 (2) Nx∧Pxy→ Ny (3) ∀x∀y∀z(Nx∧Pxy∧Pxz→ y = z) (4) ∀x∀y∀z(Nx∧Ny∧Pxz∧Pyz→ x = y) (5) ¬∃x(Nx∧Px0) (6) ∀x(Nx→∃y(Pxy)) (7) ∀F(F0∧∀x∀y(Nx∧Fx∧Pxy→ Fy)→∀x(Nx→ Fx) If (slightly non-standardly) we ...

Discriminants and Ramified Primes

has some ei greater than 1. If every ei equals 1, we say p is unramified in K. Example 1.1. In Z[i], the only prime which ramifies is 2: (2) = (1 + i)2. Example 1.2. Let K = Q(α) where α is a root of f(X) = T 3 − 9T − 6. Then 6 = α3 − 9α = α(α− 3)(α+ 3). For m ∈ Z, α+m has minimal polynomial f(T −m) in Q[T ], so NK/Q(α+m) = −f(−m) = m3 − 9m+ 6 and the principal ideal (α−m) has norm N(α−m) = |m ...

Finitely Ramified Iterated Extensions

Let p be a prime number, K a number field, and S a finite set of places of K. Let KS be the compositum of all extensions of K (in a fixed algebraic closure K) which are unramified outside S, and put GK,S = Gal(KS/K) for its Galois group. These arithmetic fundamental groups play a very important role in number theory. Algebraic geometry provides the most fruitful known source of information conc...