Marlowe or Shakespeare? Determining the Authorship of a Mysterious Play

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Marlowe or Shakespeare? Determining the
Authorship of a Mysterious Play

• Chapter 9, Exercise 4
• Bill Camarinos
• Andy Gibbons

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Background

• Virtually every year for the past one hundred
  years a play or other work of literature is found
  somewhere in the United Kingdom ostensibly
  written by William Shakespeare or Christopher
  Marlowe.
• Specialists in Elizabethan literature typically
  conclude that these finds are frauds.

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Shakespeare and Marlowe

• Both were born in 1564.
• Shakespeare died in 1616.
• Marlowe supposedly killed in a tavern brawl in
  1593, but many suspect that this death was
  staged. There is enough doubt that Marlowes
  window in Westminster Abbeys Poets corner has
  the dates of his life as 1564-1593?

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Shakespeare Authorship Controversy

• Some maintain that someone other than Shakespeare
  was the true author of the Shakespearean canon.
• Among the candidates
• Edward DeVere, 17th Earl of Oxford.
• Francis Bacon.
• Queen Elizabeth I
• Christopher Marlowe
• Every year there is a court-type competition in
  Washington among leading attorneys to prove who
  is the author. Supreme Court Justices sit as
  judges.
• Separately, there is a prize, the Hoffman prize,
  that will be given to whoever can convince the
  world that Christopher Marlowe wrote the works
  attributed to Shakespeare.

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Our Assumptions

• Shakespeare, not Marlowe or anyone else, wrote
  the Shakespearean canon.
• The mystery play which has been found was
  definitely written by either Marlowe or
  Shakespeare. It is not another of the frauds
  that keep turning up.

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What we have to work with

• An electronic version of a play of unknown
  authorship
• Electronic versions of all known works of William
  Shakespeare
• Electronic versions of all known works of
  Christopher Marlowe

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How we propose to proceed

• Investigate how quantitative techniques and
  computers have been used to solve authorship
  attribution problems in the past.
• Determine which techniques have the greatest
  probabilities of success.
• Design a process for applying the selected
  techniques using what we have at our disposal.
• Determine the true authorship.

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Early and Simple Quantitative Approaches

• Compare word length. Frequency distribution of
  word lengths in works by the authors in question.
• Average number of syllables per word.
• Sentence length
• Percentages of different parts of speech

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What is the result of applying the simple tests?

• Many are better at identifying types of writing
  (e.g. narrative vs. drama) than they are at
  distinguishing one author from another.
• The word-length test was actually applied to
  Shakespeare and Marlowe and the result was
  Christopher Marlowe agrees with Shakespeare
  about as well as Shakespeare agrees with himself.

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Other Methods

• Function-word approach. Focus on the frequency
  with which different articles, conjunctions and
  prepositions (context-free words) are used.
  Frequencies often vary significantly from one
  author to another.
• Measure pace - the rate of introduction of new
  vocabulary into the texts.
• Focus on words used only once or twice.

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Other Methods (Continued)

• Cumulative Sum Charts (cusums or qsums)- Compare
  two features using a chart
• one of which is sentence length
• the other of which is something like the number
  of two or three letter words in each sentence
• similar chart patterns suggest uniform
  authorship.
• chart patterns for a different author will diverge

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Other Methods (Continued)

• Use of Neural Networks
• Neural Networks have powerful pattern-recognition
  capabilities
• Network is trained or calibrated using data
  from a known author ( such as the known works of
  Shakespeare or Marlowe)
• The network can then classify doubtful text (such
  as the mystery play) based on what it has
  learned.
• Two researchers reported success using neural
  networks to compare Shakespeare and Marlowe.

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What Previous Authorship Attribution Studies Have
Shown

• The simplest tests (e.g. word length analysis)
  dont work.
• Some only slightly more complex tests (e.g.
  function-word analysis) have had some success.
• Combinations of tests, even if some are quite
  simple, have a high probability of success.
• Success in attribution is much more likely when
  only two candidate authors are present.
• Success becomes even more likely if there is a
  large body of known material available (and we
  have all the known works of both Shakespeare and
  Marlowe).
• With leading edge techniques that you really
  dont understand-Dont try this at home.

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Methods We Considered

• Even though they show a lot of promise we ruled
  out neural networks since we have no experience
  at all in using them.
• We also considered data mining.
• Data are stored in a data warehouse.
• Query and reporting tools, multidimensional
  analysis tools, and intelligent agents are used
  to analyze the data.
• For example, intelligent agents could be fitted
  with an algorithm designed to find patterns.
• We decided that data mining was overkill for the
  problem at hand.

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Method We Selected

• Use a readily available relational data base,
  Oracle, as our analysis and reporting tool.
• Relational data bases organize data into tables
  which are related to one another using key
  fields.
• Some of the tables we would create
• Words used by Shakespeare.
• Troublesome words used in the plays
• Weird words used by Shakespeare
• Examples of each authors use of verse and meter.
  

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Method We Selected (Continued)

• Structured Query Language (SQL) or the associated
  Query by Example (QBE) would be used to query the
  data.
• We would define how many points of similarity in
  use of language, verse, etc. would be needed to
  establish authorship. For example, samples of
  Shakespeares and Marlowes use of iambic
  pentameter in their known works would be compared
  to that in the mystery play
• Oracles Report Generator would be used to create
  a report showing how the mystery play compares
  with the known texts based on the criteria we
  established.

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Conclusion

• Our task has been a fascinating, and fun, one.
• Our survey of the work previously done showed
  that Computers and Linguistics have come a way
  and that computers can be used to help solve the
  type of authorship attribution questions that
  scholars have debated for years.
• We believe that using a powerful relational data
  base to perform the kinds of tests that have
  proven most successful in previous studies would
  convince the quantitatively oriented community of
  the authorship of the mystery play.
• We would seek validation of our results from an
  Elizabethan scholar who specializes in the works
  of Shakespeare and Marlowe. This would give
  credence to our results among those who are
  dubious of quantitative approaches.