Question: When was the prince who attended NHH Symposium with The Norwegian king, Harald V  born? 
Context: The Norwegian Aviation Museum (Norwegian: "Norsk luftfartsmuseum" ) was opened by King Harald V on May 15, 1994.  It is the Norwegian national museum of aviation and also the largest aviation museum in the Nordic countries, covering around 10,000 m² .  Situated in Bodø, Nordland the building is shaped like a huge propeller and contains both a civil and a military collection of aircraft. Haakon, Crown Prince of Norway (] ; Haakon Magnus; born 20 July 1973) is the only son and younger child of King Harald V and heir apparent to the throne of Norway. Leif Birger Methlie (born 5 April 1939) is a Norwegian mechanical engineer, organizational theorist, and Professor Emeritus at the Norwegian School of Economics (NHH).  He was rector at NHH from 1990-1995. Astrid Sandvik (born 1 October 1939) is a Norwegian Alpine skier who finished tied for sixth place (with fellow Norwegian and 1958 Holmenkollen medalist Inger Bjørnbakken) in the women's slalom at the 1956 Winter Olympics in Cortina d'Ampezzo.  In 1963, Sandvik was awarded the Holmenkollen medal (shared with Alevtina Kolchina, Pavel Kolchin, and Torbjørn Yggeseth.) .  Sandvik is one of only eleven non-Nordic skiers to win the Holmenkollen medal (Stein Eriksen, King Haakon VII, Boghild Niskin, Inger Bjørnbakken, Sandvik, King Olav V, Erik Håker, Jacob Vaage, King Harald V, and Queen Sonja (all from Norway); and Ingemar Stenmark (Sweden) are the others.) . "Mitt lille land" (in English: "My Little Country" or "My Small Country" ) is a song by Ole Paus, written in 1994 as a lyrical description of Norway.  The song gained strong popularity following the 2011 Norway attacks, which led to it being described by the media as "the new national anthem."  According to the NRK, the song "came to symbolize the sorrow many people went through."  The song featured most prominently in all the memorial ceremonies following the attacks.  The NRK memorial concert (30 July 2011) following the attacks was named "Mitt lille land," and the concert opened with "Mitt lille land" sung by Maria Mena.  The national memorial ceremony (21 August 2011) was opened with "Mitt lille land" sung by Susanne Sundfør, followed by a speech by King Harald V.  On the Norwegian Constitution Day in 2012, the NRK broadcast was opened with "Mitt lille land."  The Norwegian People's Aid and Sony Music released a memorial album titled "Mitt lille land" and Gyldendal Norsk Forlag published a memorial book also titled "Mitt lille land" during the autumn of 2011.  Numerous Norwegian artists have recorded cover versions of this song, among them Sondre Bratland, Christine Guldbrandsen, Maria Solheim, Thomas Dybdahl, Mari Boine, Anne Grete Preus, Haddy N'jie, Kurt Nilsen, D.D.E., Sølvguttene, Tone Damli Aaberge and Maria Mena. The Battle of Niså ("Slaget ved Niså") was a naval battle fought on 9 August 1062 between the forces of Norwegian king Harald Hardrada and king Sweyn II of Denmark.  Harald had claimed the Danish throne since 1047, and had launched raids into Denmark ever since.  With his invasion in 1062, he wanted to decisively defeat the Danes, and thus finally be able to conquer Denmark.  The battle was won clearly by the Norwegians, but since many Danes managed to escape, including Sweyn, it proved indecisive in Harald's attempt to conquer Denmark. The Norwegian Lutheran Memorial Church of Minneapolis ("Norwegian" "Den Norske Lutherske Mindekirke"), better known as Mindekirken, is a Lutheran church in Minneapolis in the U.S. state of Minnesota.  It is one of two American churches still using Norwegian as a primary liturgical language, the other being Minnekirken in Chicago, Illinois.  King Harald V of Norway is the church's patron. The NHH Symposium is a biennial, two day business conference held at the Norwegian School of Economics (NHH), Bergen, Norway.  The inaugural meeting, inspired by the St. Gallen Symposium, was held in 1983.  The meeting is convened by volunteer students.  Keynote speakers have included Edward Heath and Henry Kissinger.  The Norwegian king, Harald V attended in 1995 and +Haakon, Crown Prince of Norway in 2007 and 2009. Julius Paltiel (4 July 1924 – 7 March 2008) was one of the 26 Norwegian Jews who returned from Auschwitz.  For their tireless service in telling about the atrocities in the Nazi extermination camps, both Paltiel and his widow were awarded St. Olav's Medal, he in 2004 and she in 2016.  Paltiel was given a Norwegian state funeral, attended by King Harald V. The Medal for Heroic Deeds was instituted by royal resolution on 19 August 1885 and is awarded for honorable actions in saving lives or a comparable act.  There was originally three classes, but from 1905 the medal has been awarded in gold and silver.  To be awarded in gold the recipient must have committed an unusually notable rescue of life where the rescuer's life was put at risk.  The medal is surmountet by the Crown of Norway and the adverse side features the portrait, name and title of the reigning monarch.  At present the portrait is of King Harald V of Norway and the inscription reads «Harald den 5, Norges Konge» ("Harald the fifth, King of Norway").  The reverse features an oak reaf and the words «For edel dåd» ("For noble deed").  The ribbon is in the national colours of Norway: red, white and blue.
Answer: 20 July 1973