A machine-learning algorithm developed by Czech researcher Petr Plechac has finally put an end to the century-old debate about the authorship of Shakespeare’s Henry VIII. Being one of the last works by Shakespeare, scholars like James Spedding had pointed out that the legendary play writer did not write almost half of the play, rather by John Fletcher, who was Shakespeare’s successor at the King’s Men theatre company. Petr Plechac’s algorithm finally confirms this 169-year-old theory. 

Petr Plechac, from the Czech Academy of Sciences in Prague, trained the AI algorithm on scenes from Shakespeare’s later plays Coriolanus, Cymbeline, The Winter’s Tale and The Tempest, and on Fletcher’s Valentinian, Monsieur Thomas, The Woman’s Prize and Bonduca. The research team employed a combined analysis of vocabulary and versification together with machine learning techniques to determine which authors took part in the writing of the play and what were their relative contributions.

The process is explained in the paper titled “Relative contributions of Shakespeare and Fletcher in Henry VIII: An Analysis Based on Most Frequent Words and Most Frequent Rhythmic Patterns.”

“Unlike most previous studies, we go beyond the attribution of particular scenes and use the rolling attribution approach to determine the probabilities of authorship of pieces of texts, without respecting the scene boundaries. Our results highly support the canonical division of the play between William Shakespeare and John Fletcher proposed by James Spedding, but also bring new evidence supporting the modifications proposed later by Thomas Merriam”, writes Plechac.

Some of the apparent differences in writing style the algorithm spotted include Fletcher’s frequent use of a similar set of words to fill out the last beat in a line of iambic pentameter as well as his application of “ye” where Shakespeare would write “you.” 

In conclusion to his paper, Plechac points out that “the combined versification-based and word-based models trained on 17th century English drama yield a high accuracy of authorship recognition. We can thus state with high reliability that H8 (Henry VIII) is a result of a collaboration between William Shakespeare and John Fletcher, while the participation of Philip Massinger is rather unlikely.”