Wilhelm Wirtinger
...that Austrian mathematician Wilhelm Wirtinger (1865–1945) showed how to compute the fundamental group of a knot?
...that <a href="./Austria" id="mwAfo" rel="mw:WikiLink" title="Austria">Austrian</a> <a href="./Mathematician" id="mwAfs" rel="mw:WikiLink" title="Mathematician">mathematician</a> <b id="mwAfw"><a href="./Wilhelm_Wirtinger" id="mwAf0" rel="mw:WikiLink" title="Wilhelm Wirtinger">Wilhelm Wirtinger</a></b> (<a href="./1865" id="mwAf4" rel="mw:WikiLink" title="1865">1865</a><span id="mwAf8" typeof="mw:Entity">–</span><a href="./1945" id="mwAgA" rel="mw:WikiLink" title="1945">1945</a>) showed how to compute the <a href="./Knot_group" id="mwAgE" rel="mw:WikiLink" title="Knot group">fundamental group</a> of a <a href="./Knot_theory" id="mwAgI" rel="mw:WikiLink" title="Knot theory">knot</a>?