48 Normat 57:1, 48 (2009)
Summary in English
Morten Eide, Abel, de elliptiske funk-
sjoner og lemniskaten (Norwegian).
Abel discovered that if p = 2
n
+ 1 is a
prime, a lemniscate can be divided into
p parts of equal lengths, using ruler and
compass. This result is explored from an
elementary point of view, introducing
the lemniscate, the integral expression
for its arclength and from that its con-
nection to elliptic functions, and conclu-
ding by considering the most elementa-
ry cases p = 2, 3 using explicit formulas
for the doubling and tripling of argu-
ments for elliptic functions.
Ulf Persson, Modulirum för trianglar
(och tetrahedra) (Swedish).
This is the introductory part of a plan-
ned series on triangles (and tetrahedra).
Modulispace, via group actions and fun-
damental domains are introduced in a
very elementary context. Classical func-
tions, such as the radi of inscribed and
circumscribed circles or the areas, de-
fined on the space of triangles are expli-
citly computed in the relevant variables.
Christer Bergsten, Tvillingcirklar
(Swedish).
This ties in with previous articles on
the arbelos of Archimdes, but instead
of starting with two tangent circles, en-
closed in a common tangent circle, no
conditions are imposed on the two. We
then get two cases, whether the circles
intersect or not, and a detailed study
is made of the ensuing circles. Much
of the motivation for this paper is how
the problems can be used to illustrate
the power of various dynamical geome-
try software available on the market sine
the 80’s.
Martin Gardner An Amazing Mathe-
matical Trick with Cards. (English).
A simple but striking card trick is pre-
sented by the old magician, and the re-
aders are challenged to explain how it
works.
Peter Lindqvist Arild Stubhaug: Gös-
ta Mittag-Leffler. (Swedish).
Gösta Mittag-Leffler (1846-1927) was
the father of Swedish mathematics. He
was not only a mathematician but al-
so an enterprising businessman and po-
litician, who played a central role in
Swedish Society, especially during the
era of Oscar II (1872-1907). He was one
of the founders of what later would be-
come Stockholm University, his contacts
with the leading mathematicians of his
day, enabled him to launch Acta Mathe-
matica successfully, and he built a mo-
nument to himself and the disinterested
study of mathematics in his villa at the
Stockholm suburb of Djursholm, whe-
re he collected his impressive library
and which in recent decades has become
a well-known research institute. In the
words of G.H.Hardy There have been
greater mathematicians during the last
fifty years, but no one who has done
in his way more for mathematics.. Alt-
hough largely forgotten today, except
by mathematicians, this ambitious bio-
graphy brings to life an era painting a
vivid panorama involving most of the
central players of Swedish society at the
time.
