New answers tagged

1 vote
Accepted

Express Two way ANOVA with interaction as matrix form

We have $$y_{ijk}-\overline y=(\overline y_{i\cdot\cdot}-\overline y)+(\overline y_{\cdot j\cdot}-\overline y)+(\overline y_{ij\cdot}-\overline y_{i\cdot\cdot}-\overline y_{\cdot j\cdot}+\overline y)+(...
user avatar
  • 15.3k
5 votes
Accepted

For a number field $K$, is an integer a sum of two $K$'s elements squares iff it is a sum of two integer squares?

This is not true. For example, let $K=\Bbb{Q}(i)$ with $\mathcal{O}_K=\Bbb Z[i]$. Then $$ i = \left(\frac{1+i}{2}\right)^2 + \left(\frac{1+i}{2}\right)^2. $$ This shows $i$ is a sum of two squares in $...
user avatar

Top 50 recent answers are included