> Hans Åberg <mailto:haberg-1@telia.com>
> 21. Mai 2016 um 16:09
> The typing environment does not seem to work on non-ASCII characters: 
> below, ∀, ≔ and ∈ drop out. Perhaps not available in monospace, 
> substituting nothing.
>
> \setupbodyfont[xits,10pt]
>
> \starttyping
> ∀(i, k) ∈ I×K: C(i, k) ≔ ∑_(j∈J) A(i, j)·B(j, k)
> \stoptyping
You need a font which has the necessary symbols or you take the missing 
one from another font but in this case you should look for one which has 
a similar style as the main font (which is not the case in my example).

\definefallbackfamily [moremath] [tt] [DejaVu Sans Mono] 
[range=mathematicaloperators]
\definefontfamily     [moremath] [tt] [Latin Modern Mono]
%\definefontfamily     [moremath] [mm] [Latin Modern Math]

\setupbodyfont[moremath,10pt]

\starttext

\starttyping
∀(i, k) ∈ I×K: C(i, k) ≔ ∑_(j∈J) A(i, j)·B(j, k)
\stoptyping

\stoptext

PS. Your example is missing the \starttext and \stoptext.

Wolfgang