15

Answers

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5

Hyperreal finitely-additive measure on [0,1) assigning $b-a$ to $[a,b)$ or $(a,b]$ and infinitesimals to singletons

4

Is there a statement equivalent to a sentence admitting $(\alpha^{+n},\alpha)$?

5

Sizes of bases of vector spaces without the axiom of choice

1

Ordered sum of posets

3

The consistency of Martin’s Axiom

1

Non standard algebraic geometry: shadows of varieties

5

Direct construction of the integers

3

Topology generated by the collection of open sets

4

Taking “Zooming in on a point of a graph” seriously.

5

How misleading is it to regard $\frac{dy}{dx}$ as a fraction?

4

Consistency strengths related to the perfect set property

1

Entropy of a measure

3

Is there a least-fixed-point formulation of inaccessible cardinals?

3

Nonstandard models of PA of large cardinal size

6

Can Sierpinski’s anisotropic bicolouring of the plane, assuming the continuum hypothesis (CH), be extended to three dimensions?