Hi Ursula,

I think you mean the so-called end of the proof sign, or QED (Quod Erat Demonstrandum). You can use this:

\definesymbol[QED][\mathematics{\square}]
\def\qed{\wordright{\symbol[QED]}}
\starttext
This is the end of our proof. \qed
\stoptext

In principle it is included in ConTeXt, but it seems that in the latest version I have (2024.01.23), the command \qed is broken.

Best regards: Otared

> On 8 Feb 2024, at 12:23, Ursula Hermann <ursula.hermann@univie.ac.at> wrote:
> 
> Dear List, 
> 
> I am at Home  and have the following example.:
> 
> \starttext
> \margintext {1.1.1}
> {\bf Beispiel 3.2.17 (Vertauschung von All- und Existenzquantor).}
> \par
> {\it Sei M die Menge aller Männer und F die Menge aller Frauen. Die
> Aus-\par
> sage h(m, f) sei ”m ist verliebt in f“. Unter diesen Voraussetzungen
> machen Sie sich die Bedeutung der beiden Aussagen klar.\startalignment[right]\square\stopalignment}\stoptext}
> 
> There should be a sign like this □ at the end of the proof. 
> 
> Uschi
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Otared Kavian
e-mail: otared@gmail.com
Phone: +33 6 88 26 70 95