3,228 reputation
1833
bio website jakitoimgeisterhaus.blogspot.…
location Munich, Germany
age 38
visits member for 3 years, 2 months
seen 14 mins ago

My past research interests included differential algebraic equations, nonlinear analysis and relations between symmetries and structural properties.

I recently investigated hierarchical structures, starting from group cohomology, continuing with semi-group theory and ending with lattices and universal algebra.


Jul
7
accepted Which biased random sources can be obtained from an unbiased one?
Jun
25
accepted Are these two equivalences really as “immediate” as Jean-Yves Girard claims?
May
17
accepted Can Goodstein's theorem be expressed as an axiom or axiom scheme in PA?
May
4
accepted Computing 2d radially symmetric Fourier transforms (with Wolfram Alpha)
May
3
accepted Can the consistency of ZF be proved in MK?
Apr
26
accepted Is every “almost” isomorphism an isomorphism?
Apr
16
accepted Which constructions on a category are still interesting for a groupoid?
Mar
12
accepted Are these adjoint functors to/from the category of monoids with semigroup homomorphisms?
Feb
3
accepted Which of these constructions are left adjoints?
Jan
22
accepted Relation between concept lattice and Dedekind–MacNeille completion
Aug
23
accepted Existence of maximal boolean-algebra sublattice (preserving top and bottom) of finite distributive lattice
Jun
9
accepted How to express the powers of two by a Diophantine equation?
Jun
7
accepted Which set theories without the power set axiom are used occasionally?
May
5
accepted Why is quantified propositional logic not part of first-order logic?
May
4
accepted Monadic second order logic without constants, functions and equality
May
4
accepted Paradox: Any set theory without universe set is not a model of itself
Apr
6
accepted Are there simple models of Euclid's postulates that violate Pasch's theorem or Pasch's axiom?
Mar
15
accepted Are Horn clauses always universally quantified?
Jan
3
accepted Can second order logic express each (computable) infinitary logic sentence?
Dec
20
accepted Polynomial bounded real part of an entire function