Die Walküre
Encyclopedia
Die Walküre WWV 86B, is the second of the four opera
Opera
Opera is an art form in which singers and musicians perform a dramatic work combining text and musical score, usually in a theatrical setting. Opera incorporates many of the elements of spoken theatre, such as acting, scenery, and costumes and sometimes includes dance...

s that form the cycle Der Ring des Nibelungen
Der Ring des Nibelungen
Der Ring des Nibelungen is a cycle of four epic operas by the German composer Richard Wagner . The works are based loosely on characters from the Norse sagas and the Nibelungenlied...

 (The Ring of the Nibelung), by Richard Wagner
Richard Wagner
Wilhelm Richard Wagner was a German composer, conductor, theatre director, philosopher, music theorist, poet, essayist and writer primarily known for his operas...

. Die Walküres best-known excerpt is the "Ride of the Valkyries
Ride of the Valkyries
The Ride of the Valkyries is the popular term for the beginning of Act III of Die Walküre, the second of the four operas by Richard Wagner that comprise Der Ring des Nibelungen. The main theme of the Ride, the leitmotif labelled Walkürenritt, was first written down by the composer on 23 July 1851...

".

Wagner took his tale from the Norse mythology
Norse mythology
Norse mythology, a subset of Germanic mythology, is the overall term for the myths, legends and beliefs about supernatural beings of Norse pagans. It flourished prior to the Christianization of Scandinavia, during the Early Middle Ages, and passed into Nordic folklore, with some aspects surviving...

 told in the Volsunga Saga and the Poetic Edda
Poetic Edda
The Poetic Edda is a collection of Old Norse poems primarily preserved in the Icelandic mediaeval manuscript Codex Regius. Along with Snorri Sturluson's Prose Edda, the Poetic Edda is the most important extant source on Norse mythology and Germanic heroic legends, and from the early 19th century...

.

It received its premiere at the National Theatre Munich on 26 June 1870 at the insistence of King Ludwig II of Bavaria
Ludwig II of Bavaria
Ludwig II was King of Bavaria from 1864 until shortly before his death. He is sometimes called the Swan King and der Märchenkönig, the Fairy tale King...

. It premiered in Wagner's Bayreuth Festival
Bayreuth Festival
The Bayreuth Festival is a music festival held annually in Bayreuth, Germany, at which performances of operas by the 19th century German composer Richard Wagner are presented...

 as part of the complete cycle on 14 August 1876. The opera made its United States premiere at the Academy of Music in New York on 2 April 1877.

Composition

Although Die Walküre is the second of the Ring operas, it was the third in order of conception. Wagner worked backwards from planning an opera about Siegfried
Sigurd
Sigurd is a legendary hero of Norse mythology, as well as the central character in the Völsunga saga. The earliest extant representations for his legend come in pictorial form from seven runestones in Sweden and most notably the Ramsund carving Sigurd (Old Norse: Sigurðr) is a legendary hero of...

's death, then deciding he needed another opera to tell of Siegfried's youth, then deciding he needed to tell the tale of Siegfried's conception and of Brünnhilde's attempts to save his parents, and finally deciding he also needed a prelude that told of the original theft of the Rheingold and creation of the ring.

Wagner intermingled development of the text of these last two planned operas, i.e. Die Walküre, originally entitled Siegmund und Sieglinde: der Walküre Bestrafung (Siegmund and Sieglinde: the Valkyrie's Punishment) and what became Das Rheingold
Das Rheingold
is the first of the four operas that constitute Richard Wagner's Der Ring des Nibelungen . It was originally written as an introduction to the tripartite Ring, but the cycle is now generally regarded as consisting of four individual operas.Das Rheingold received its premiere at the National Theatre...

. Wagner had first written of his intention to create a trilogy of operas in the August 1851 draft of "Eine Mittheilung an meine Freunde" (A Communication to My Friends
A Communication to My Friends
"Eine Mittheilung an meiner Freunde", usually referred to in English by its translated title of "A Communication to My Friends", is an extensive autobiographical work by Richard Wagner, published in 1851, in which he sought to justify his innovative concepts on the future of opera in general, and...

), but did not produce any sketches of the plot of Siegmund and Sieglinde until November. The following Summer, Wagner and his wife rented the Pension Rinderknecht, a pied-à-terre on the Zürichberg
Zürichberg
The Zürichberg is a wooded hill rising to 679 metres , overlooking Lake Zurich and located immediately to the east of the City of Zurich in Switzerland, between the valleys of the Limmat and the Glatt rivers...

 (now Hochstrasse 56–58 in Zürich). There he worked on the prose draft of Die Walküre, an extended description of the story including dialogue between 17 and 26 May 1852 and the verse draft between 1 June and 1 July. It was between these drafts that Wagner made the decision not to introduce Wotan in Act I, instead leaving the sword the god had been going to bring on stage already embedded in the tree before the action starts. The fair copy of the text was completed by 15 December 1852.

Even before the text of the Ring was finalised, Wagner had begun to sketch some of the music. On 23 July 1851 he wrote down on a loose sheet of paper what was to become the best-known leitmotif in the entire cycle: the theme from the "Ride of the Valkyries
Ride of the Valkyries
The Ride of the Valkyries is the popular term for the beginning of Act III of Die Walküre, the second of the four operas by Richard Wagner that comprise Der Ring des Nibelungen. The main theme of the Ride, the leitmotif labelled Walkürenritt, was first written down by the composer on 23 July 1851...

" (Walkürenritt). Other early sketches for Die Walküre were made in the summer of 1852. But it was not until 28 June 1854 that Wagner began to transform these into a complete draft of all three acts of the opera. This preliminary draft (Gesamtentwurf) was completed by 27 December 1854. Much of the work of this stage of development of the opera overlapped with work on the final orchestral version of Das Rheingold.

As Wagner had included some indication of the orchestration in the draft, he decided to move straight on to developing a full orchestral score in January 1855 without bothering to write an intermediate instrumentation draft as he had done for Das Rheingold. This was a decision he was soon to regret, as numerous interruptions including a four month visit to London made the task of orchestrating more difficult than he had expected. If he allowed too much time to elapse between the initial drafting of a passage and its later elaboration, he found that he could not remember how he had intended to orchestrate the draft. Consequently some passages had to be composed again from scratch. Wagner, nevertheless, persevered with the task and the full score was finally completed on 20 March 1856. The fair copy was begun on 14 July 1855 in the Swiss resort of Seelisberg
Seelisberg
Seelisberg is a municipality in the canton of Uri in Switzerland.-History:The Rütli meadow, according to legend the site of the original oath foundational to the Old Swiss Confederacy, is situated in the territory of the municipality....

, where Wagner and his wife spent a month. It was completed in Zürich on 23 March 1856, just three days after the completion of the full score.

Roles

Role Voice type
Voice type
A voice type is a particular kind of human singing voice perceived as having certain identifying qualities or characteristics. Voice classification is the process by which human voices are evaluated and are thereby designated into voice types...

Premiere cast
26 June 1870
(Conductor
Conducting
Conducting is the art of directing a musical performance by way of visible gestures. The primary duties of the conductor are to unify performers, set the tempo, execute clear preparations and beats, and to listen critically and shape the sound of the ensemble...

: Franz Wüllner
Franz Wüllner
Franz Wüllner was a German composer and conductor. He led the premieres of Richard Wagner's operas Das Rheingold and Die Walküre, but was much criticized by Wagner himself, who greatly preferred the more celebrated conductors Hans von Bülow and Hermann Levi.Wüllner was born in Münster and studied...

)
Cast at premiere of complete cycle
14 August 1876
(Conductor: Hans Richter
Hans Richter (conductor)
Hans Richter was an Austrian orchestral and operatic conductor.-Biography:Richter was born in Raab , Kingdom of Hungary, Austro-Hungarian Empire. His mother was opera-singer Jozsefa Csazenszky. He studied at the Vienna Conservatory...

)
Humans
Siegmund tenor
Tenor
The tenor is a type of male singing voice and is the highest male voice within the modal register. The typical tenor voice lies between C3, the C one octave below middle C, to the A above middle C in choral music, and up to high C in solo work. The low extreme for tenors is roughly B2...

Heinrich Vogl
Heinrich Vogl
Heinrich Vogl was a German operatic heldentenor.He played the role of Loge in Richard Wagner's Das Rheingold at Munich Court Opera on September 22, 1869, with his wife, Therese Vogl, playing the role of Wellgunde. He also played the role of Siegmund in Wagner's Die Walküre, also at Munich, on June...

Albert Niemann
Albert Niemann (tenor)
Albert Wilhelm Karl Niemann was a leading German tenor opera singer especially associated with the operas of Richard Wagner...

Sieglinde soprano
Soprano
A soprano is a voice type with a vocal range from approximately middle C to "high A" in choral music, or to "soprano C" or higher in operatic music. In four-part chorale style harmony, the soprano takes the highest part, which usually encompasses the melody...

Therese Vogl
Therese Vogl
Therese Vogl was a German operatic soprano.-Life:Vogl was born Therese Thoma in Tutzing, Bavaria, where she also spent the last years of her life. In 1868, she married the leading dramatic tenor Heinrich Vogl and they henceforth appeared on stage together on many occasions...

Josephine Schefsky
Josephine Schefsky
Josephine Schefsky was an opera singer who had an active career during the latter half of the 19th century. Possessing a powerful voice with a wide vocal range, she tackled roles from both the soprano and mezzo-soprano repertoires...

Hunding bass
Bass (voice type)
A bass is a type of male singing voice and possesses the lowest vocal range of all voice types. According to The New Grove Dictionary of Opera, a bass is typically classified as having a range extending from around the second E below middle C to the E above middle C...

Kaspar Bausewein
Kaspar Bausewein
Kaspar Bausewein was a German operatic bass who was active at the Bavarian State Opera from 1858 through 1900. While there he notably portrayed several characters in the world premieres of operas composed by Richard Wagner...

Josef Niering
Gods
Wotan bass-baritone
Bass-baritone
A bass-baritone is a high-lying bass or low-lying "classical" baritone voice type which shares certain qualities with the true baritone voice. The term arose in the late 19th century to describe the particular type of voice required to sing three Wagnerian roles: the Dutchman in Der fliegende...

August Kindermann
August Kindermann
August Kindermann was a German bass-baritone singer and regisseur, particularly noted for his performances in the operas of Richard Wagner. He began his career singing in the chorus of the Berlin State Opera in 1836 and made his solo debut there in 1837 in a small role in Spontini's Agnes von...

Franz Betz
Franz Betz
Franz Betz was a German bass-baritone opera singer who sang at the Berlin State Opera from 1859 to 1897. He was particularly known for his performances in operas by Richard Wagner and created the role of Hans Sachs in Die Meistersinger von Nürnberg.-Biography:Franz Betz was born in Mainz and...

Fricka mezzo-soprano
Mezzo-soprano
A mezzo-soprano is a type of classical female singing voice whose range lies between the soprano and the contralto singing voices, usually extending from the A below middle C to the A two octaves above...

Anna Kaufmann
Anna Kaufmann
Anna Kaufmann was a German operatic soprano who was a principal artist at the Bavarian State Opera in Munich from 1869 to 1872. Just prior to her appointment the great soprano Mathilde Mallinger had left the Bavarian State Opera and Kaufmann succeeded her in the roles of Elsa in Richard Wagner's...

Friederike Grün
Friederike Grün
Friederike Grün was a German operatic soprano who had an active career during the latter half of the 19th century. Possessing a powerful voice with a wide vocal range, she sang a broad repertoire that encompassed Italian, French, and German opera...

Valkyries
Brünnhilde soprano Sophie Stehle
Sophie Stehle
Sophie Stehle was a German operatic soprano.She was born in Sigmaringen and was a member of the Bavarian State Opera in Munich from 1860 to 1874. While there she created the roles of Fricka in Richard Wagner's Das Rheingold on 22 September 1869 and Brunhilde in Wagner's Die Walküre on 26 June 1869...

Amalie Materna
Amalie Materna
Amalie Materna was an Austrian operatic soprano. While possessing a famously powerful voice, Materna also maintained a youthful bright vocal timbre throughout her career which spanned for three decades...

Gerhilde soprano Karoline Lenoff Marie Haupt
Marie Haupt
Marie Haupt was a German operatic soprano who had an active career during the latter half of the 19th century. She is best remembered today for portraying several roles in the first complete presentation of Richard Wagner's The Ring Cycle at the very first Bayreuth Festival in 1876.-Biography:Born...

Ortlinde soprano Henriette Müller Marie Lehmann
Waltraute mezzo-soprano Hemauer Luise Jaide
Luise Jaide
Luise Jaide was a German operatic mezzo-soprano who had an active career during the latter half of the 19th century...

Schwertleite contralto
Contralto
Contralto is the deepest female classical singing voice, with the lowest tessitura, falling between tenor and mezzo-soprano. It typically ranges between the F below middle C to the second G above middle C , although at the extremes some voices can reach the E below middle C or the second B above...

Emma Seehofer
Emma Seehofer
Emma Seehofer was a German operatic contralto who was a principal artist at the Bavarian State Opera in Munich from 1854 to 1887. She created the roles of Erda in Richard Wagner's Das Rheingold on 22 September 1869 and Schwertleite in Wagner's Die Walküre on 26 June 1869. She was also highly...

Johanna Jachmann-Wagner
Johanna Jachmann-Wagner
Johanna Jachmann-Wagner or Johanna Wagner was a mezzo-soprano singer, tragédienne in theatrical drama, and teacher of singing and theatrical performance who won great distinction in Europe during the third quarter of the 19th century...

Helmwige soprano Anna Possart-Deinet
Anna Deinet
Anna Deinet was a German operatic soprano who had an active career during the latter half of the 19th century. She had a lengthy career at the Bavarian State Opera where she particularly excelled in coloratura soprano roles...

Lilli Lehmann
Lilli Lehmann
Lilli Lehmann, born Elisabeth Maria Lehmann, later Elisabeth Maria Lehmann-Kalisch was a German operatic soprano of phenomenal versatility...

Siegrune mezzo-soprano Anna Eichheim Antonie Amann
Grimgerde mezzo-soprano Wilhelmine Ritter
Wilhelmine Ritter
Wilhelmine Ritter was a German operatic mezzo-soprano. Not much is known about the artist and the details about her birth and training are unknown. She was a member of the Bavarian State Opera in Munich from 1866 through 1871...

Hedwig Reicher-Kindermann
Roßweiße mezzo-soprano Juliane Tyroler Marie Lammert

Act 1

During a raging storm, Siegmund seeks shelter at the house of the warrior Hunding
Hundings
The Hundings are a legendary tribe or clan in early Germanic sources, mostly mentioned due to their feud with the Wulfings . In the Poetic Edda, Hunding is a king of the Saxons, slain by Helgi Hundingsbane. The Gesta Danorum mentions a Danish king Helgo who slew Hundingus, king of Saxony, in...

. Hunding is not present, and Siegmund is greeted by Sieglinde, Hunding's unhappy wife. Siegmund tells her that he is fleeing from enemies. After taking a drink of mead, he moves to leave, claiming to be cursed by misfortune. But Sieglinde bids him stay, saying he can bring no misfortune to the "house where ill luck lives".

Returning, Hunding reluctantly offers Siegmund the hospitality demanded by custom. Sieglinde, increasingly fascinated by the visitor, urges him to tell his tale. Siegmund describes returning home with his father one day to find his mother dead and his twin sister abducted. He then wandered with his father until parting from him as well. One day he found a girl being forced into marriage and fought with the girl's relatives. His weapons were broken and the bride was killed, and he was forced to flee to Hunding's home. Initially Siegmund does not reveal his name, choosing to call himself Wehwalt, 'filled with woe'.

When Siegmund finishes, Hunding reveals that he is one of Siegmund's pursuers. He grants Siegmund a night's stay, but they are to do battle in the morning. Hunding leaves the room with Sieglinde, ignoring his wife's distress. Siegmund laments his misfortune, recalling his father's promise that he would find a sword when he most needed it.
Sieglinde returns, having drugged Hunding's drink to send him into a deep sleep. She reveals that she was forced into a marriage with Hunding. During their wedding feast, an old man appeared and plunged a sword into the trunk of the ash tree in the center of the room, which neither Hunding nor any of his companions could remove. She expresses her longing for the hero who could draw the sword and save her. Siegmund expresses his love for her, which she reciprocates, and as she strives to understand her recognition of him, she realises it is in the echo of her own voice, and reflection of her image, that she already knows him. When he speaks the name of his father, Wälse
Volsung
In Norse mythology, Völsung was the son of Rerir and the eponymous ancestor of the ill-fortuned Völsung clan , including the greatest of Norse heroes, Sigurð...

, she declares that he is Siegmund, and that the Wanderer left the sword for him.

Siegmund now easily draws the sword forth, and she tells him she is Sieglinde, his twin sister. He names the blade "Nothung" (or needful, for this is the weapon that he needs for his forthcoming fight with Hunding). As the Act closes he calls her 'bride and sister', and draws her to him with passionate fervour.

Act 2

Wotan is standing on a rocky mountainside with Brünnhilde, his Valkyrie
Valkyrie
In Norse mythology, a valkyrie is one of a host of female figures who decides who dies in battle. Selecting among half of those who die in battle , the valkyries bring their chosen to the afterlife hall of the slain, Valhalla, ruled over by the god Odin...

 daughter. He instructs Brünnhilde to protect Siegmund in his coming fight with Hunding. Fricka
Frijjō
*Frijjō is the reconstructed name or epithet of a hypothesized Common Germanic love goddess giving rise to both Frigg and Freyja....

, Wotan's wife and the guardian of wedlock, arrives demanding the punishment of Siegmund and Sieglinde,
who have committed adultery and incest. She knows that Wotan, disguised as the mortal man Wälse, fathered Siegmund and Sieglinde. Wotan protests that he requires a free hero (i.e., one not ruled by him) to aid his plans, but Fricka retorts that Siegmund is not a free hero but Wotan's creature and unwitting pawn. Backed into a corner, Wotan promises Fricka that Siegmund will die.

Fricka exits, leaving Brünnhilde with a despairing Wotan. Wotan explains his problems: troubled by the warning delivered by Erda
Jörð
In Norse mythology, Jörð and also called Jarð as in Old East Norse, is a female jötunn. She is the mother of Thor and Meili, and the personification of the Earth. Fjörgyn and Hlôdyn are considered to be other names for Jörð...

 (at the end of Das Rheingold
Das Rheingold
is the first of the four operas that constitute Richard Wagner's Der Ring des Nibelungen . It was originally written as an introduction to the tripartite Ring, but the cycle is now generally regarded as consisting of four individual operas.Das Rheingold received its premiere at the National Theatre...

), he had seduced the earth-goddess to learn more of the prophesied doom; Brünnhilde was born to him by Erda.
He raised Brünnhilde and eight other daughters as the Valkyries, warrior maidens who gather the souls of fallen heroes to form an army against Alberich
Alberich
Alberich was a legendary sorcerer who originated in the mythology or epic sagas of the Frankish Merovingian Dynasty of the 5th to 8th century AD, and whose name means king of the elves , who possessed the ability to become invisible...

. Valhalla's
Valhalla
In Norse mythology, Valhalla is a majestic, enormous hall located in Asgard, ruled over by the god Odin. Chosen by Odin, half of those that die in combat travel to Valhalla upon death, led by valkyries, while the other half go to the goddess Freyja's field Fólkvangr...

 army will fail if Alberich should ever wield the ring
Andvarinaut
In Norse mythology, Andvaranaut is a magical ring capable of producing gold, first owned by Andvari.The mischievous god Loki tricked Andvari into giving Andvaranaut to him...

, which is in Fafner
Fafnir
In Norse mythology, Fáfnir or Frænir was a son of the dwarf king Hreidmar and brother of Regin and Ótr. In the Volsunga saga, Fáfnir was a dwarf gifted with a powerful arm and fearless soul. He guarded his father's house of glittering gold and flashing gems...

's possession. Using the Tarnhelm
Tarnhelm
Tarnhelm is the name of a magic helmet in Richard Wagner's Der Ring des Nibelungen. It is used as a cloak of invisibility by Alberich in Das Rheingold...

 the giant has transformed himself into a dragon, lurking in a forest with the Nibelung
Nibelung
The German Nibelungen and the corresponding Old Norse form Niflung is the name in Germanic and Norse mythology of the royal family or lineage of the Burgundians who settled at Worms....

 treasure. Wotan cannot wrest the ring from Fafner, who is bound to him by contract; he needs a free hero to defeat Fafner in his stead. But as Fricka pointed out, he can create only thralls (i.e. servants) to himself. Bitterly, Wotan orders Brünnhilde to obey Fricka and ensure the death of his beloved child Siegmund.

Having fled Hunding's hall, Siegmund and Sieglinde enter the mountain pass, where Sieglinde faints in guilt and exhaustion. Brünnhilde approaches Siegmund and tells him of his impending death. Siegmund refuses to follow Brünnhilde to Valhalla when she tells him Sieglinde cannot accompany him there. He draws his sword and threatens to kill both Sieglinde and himself. Impressed by his passion, Brünnhilde relents and agrees to grant victory to Siegmund instead of Hunding.

Hunding arrives and attacks Siegmund. Blessed by Brünnhilde, Siegmund begins to overpower Hunding, but Wotan appears and shatters Nothung (Siegmund's sword) with his spear. While Siegmund is thus disarmed and helpless, Hunding stabs him to death. Wotan looks down on Siegmund's body, grieving, and Brünnhilde gathers up the fragments of Nothung and flees on horseback with Sieglinde. Wotan strikes Hunding dead with a contemptuous gesture, and angrily sets out in pursuit of his disobedient daughter.

Act 3

The other Valkyrie
Valkyrie
In Norse mythology, a valkyrie is one of a host of female figures who decides who dies in battle. Selecting among half of those who die in battle , the valkyries bring their chosen to the afterlife hall of the slain, Valhalla, ruled over by the god Odin...

s assemble on the summit of a mountain, each with a dead hero in her saddlebag. They are astonished when Brünnhilde arrives with Sieglinde, a living woman. She begs them to help, but they dare not defy Wotan. Brünnhilde decides to delay Wotan as Sieglinde flees. She also reveals that Sieglinde is pregnant by Siegmund, and names the unborn son Siegfried
Sigurd
Sigurd is a legendary hero of Norse mythology, as well as the central character in the Völsunga saga. The earliest extant representations for his legend come in pictorial form from seven runestones in Sweden and most notably the Ramsund carving Sigurd (Old Norse: Sigurðr) is a legendary hero of...

.

Wotan arrives in wrath and passes judgement on Brünnhilde: she is to be stripped of her Valkyrie status and become a mortal woman, to be held in a magic sleep on the mountain, prey to any man who happens by. Dismayed, the other Valkyries flee. Brünnhilde begs mercy of Wotan for herself, his favorite child. She recounts the courage of Siegmund and her decision to protect him, knowing that was Wotan's true desire. With the words 'Der diese Liebe mir ins Herz gehaucht' (He who breathed this love into me), introducing the key of E major, she identifies her actions as Wotan's true will. Wotan consents to her last request: to encircle the mountaintop with magic flame, which will deter all but the bravest of heroes (who, as shown through the leitmotif, they both know will be the yet unborn Siegfried). Wotan lays Brünnhilde down on a rock and, in a long embrace, kisses her eyes closed into an enchanted sleep. He summons Loge
Loki
In Norse mythology, Loki or Loke is a god or jötunn . Loki is the son of Fárbauti and Laufey, and the brother of Helblindi and Býleistr. By the jötunn Angrboða, Loki is the father of Hel, the wolf Fenrir, and the world serpent Jörmungandr. By his wife Sigyn, Loki is the father of Nari or Narfi...

 (the Norse demigod of fire) to ignite the circle of flame that will protect her, then slowly departs in sorrow, after pronouncing: "Whosoever fears the point of my spear shall not pass through the fire." The curtain falls as the Magic Fire Music again resolves into E major.

Noted excerpts

  • Prelude to Act I (The opening storm)
  • Siegmund Spring Song and duet with Sieglinde (Winterstürme wichen dem Wonnemond) (Act I)
  • Prelude to Act II
  • Wotan's Monologue (Act II)
  • Brünnhilde's Announcement of Siegmund's Death (Act II)
  • "Ride of the Valkyries
    Ride of the Valkyries
    The Ride of the Valkyries is the popular term for the beginning of Act III of Die Walküre, the second of the four operas by Richard Wagner that comprise Der Ring des Nibelungen. The main theme of the Ride, the leitmotif labelled Walkürenritt, was first written down by the composer on 23 July 1851...

    " (Prelude and scene 1 ("Hojotoho! Heiaha") from Act III)
  • Brunnhilde's pleading (War es so schmählich) (Act III)
  • Wotan's Farewell (Leb' wohl) (Act III)
  • Magic Fire Music (Act III)

External links

The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.
 
x
OK