  A family $\mathcal A$ of subsets of an $n$-element set is called an eventown
(resp. oddtown) if all its sets have even (resp. odd) size and all pairwise
intersections have even size. Using tools from linear algebra, it was shown by
Berlekamp and Graver that the maximum size of an eventown is $2^{\left\lfloor
n/2\right\rfloor}$. On the other hand (somewhat surprisingly), it was proven by
Berlekamp, that oddtowns have size at most $n$. Over the last four decades,
many extensions of this even/oddtown problem have been studied. In this paper
we present new results on two such extensions. First, extending a result of Vu,
we show that a $k$-wise eventown (i.e., intersections of $k$ sets are even) has
for $k \geq 3$ a unique extremal configuration and obtain a stability result
for this problem. Next we improve some known bounds for the defect version of
an $\ell$-oddtown problem. In this problem we consider sets of size $\not\equiv
0 \pmod \ell$ where $\ell$ is a prime number $\ell$ (not necessarily $2$) and
allow a few pairwise intersections to also have size $\not\equiv 0 \pmod \ell$.

Combinatorics