Question: Who is the person that is portrayed in Leonardo da Vinci's Mona Lisa?
About the article "Mona Lisa", section "Abstract".

Candidate passages:
Portraits are natural reflection of real people.
The ability to achieve a true likeness was greatly valued until the mid-nineteenth century.
However, once photographs became common, artists could use their skills to show something about the subject that no camera could match.
In additional to showing the person, a great portrait suggests a history, personality, mood and feeling.
Leonardo da Vinci's "Mona Lisa", 1507 captures the essence of the portrait in that it is compelling, and the view feels a connection to the person who is portrayed, yet it is also mysterious. 
Yves Chaudron was a French master art forger who is alleged to have copied images of Leonardo da Vinci's Mona Lisa as part of Eduardo de Valfierno's famous 1911 Mona Lisa painting theft. 
The Isleworth Mona Lisa is a painting of the same subject as Leonardo da Vinci's Mona Lisa, at an earlier age.
Though insufficiently examined, the painting is claimed by some to be partly an original work of Leonardo dating from the early 16th century. 
Two nude paintings bearing similarities to Leonardo da Vinci's original were part of a 2009 exhibition of artwork inspired by "Mona Lisa".
Displayed at the Museo Ideale in Leonardo's hometown of Vinci, near Florence, some believe one of the paintings – dating from Leonardo's time – to be the work of Leonardo himself, and it has at times been credited to him.
Other experts theorize the painting, one of at least six known to exist, may be just another copy painted by "followers" of Leonardo.
Scholarly dispute persists as to artist, subject and origin.
The nude in question, discovered behind a wall in a private library, reportedly belonged to an uncle of Napoleon Bonaparte, who owned another of Leonardo's paintings.
Facial features bear only vague resemblance, but landscape, compositional and technical details correspond to those of the "Mona Lisa" known worldwide today.
A student and companion of Leonardo da Vinci known as Salaì painted one of the nude interpretations of "Mona Lisa" known, titled "Mona Vanna".
Salai's version is thought by some to have been "based on" the nude sometimes attributed to Leonardo, which is considered a lost work.
Discussion among experts exists as to whether Salai, known to have modeled for Leonardo, may in fact have been the sitter represented in the original "Mona Lisa".
Joos van Cleve, a Flemish artist active in the years following "Mona Lisa"'s creation, also painted a nude titled "Mona Vanna".
Though the figure portrayed in van Cleve's painting bears no resemblance to Leonardo's "Mona Lisa", the artist was known to mimic themes and techniques of Leonardo da Vinci, in this case the positioning of the figure and the delicate brushwork reminiscent of Leonardo's sfumato.
The artwork, dating to the mid-16th century, is in the collection of the National Gallery, Prague. 
Schwartz used the works of Leonardo da Vinci extensively in experiments with computers.
One notable work she created is "Mona/Leo", for which she compared the image of a Leonardo da Vinci self-portrait with the "Mona Lisa", matching the two faces feature by feature to show their underlying structural similarity.
Specifically, she replaced the right side of the "Mona Lisa" with the flipped left side of a red chalk self-portrait of Leonardo.
Superimposed lines drawn on the image showing the close alignments of the bottom of the eye, eyebrow, nose and chin prompted her to argue that the Mona Lisa is in part a cryptic self-portrait of the artist.
In further experiments along these lines, she removed the gray tones in Leonardo da Vinci's self-portrait and superimposed the "Mona Lisa" eye over it.
Not everyone is convinced by her argument for the identity of Leonardo da Vinci and the "Mona Lisa"; one common counter-argument is that the similarities are due to both portraits having been created by the same person and therefore bearing the hallmarks of a characteristic style.
Additionally, though the drawing on which Schwartz based the comparison is held to be a self-portrait, there is no firm historical evidence to support this theory.
In a similar experiment, Schwartz used a custom ray-tracing program to investigate the perspective anomalies in the drawing of da Vinci's fresco painting of the "Last Supper".
Her 3D computer-generated model showed that the perspective lines in the "Last Supper" do match up with (extend) the architecture of the refectory of Santa Maria delle Grazie in Milan where the fresco is located, but only because of certain changes Leonardo made to standard linear perspective.