Proteus verse¶
proteus_verse · permutation · validated
A line whose words can be permuted into many metrically valid variants. The checker asks two things of a line: that it scans as written, and that its words admit at least a given number of orderings that also scan.
Provenance¶
- Source: Julius Caesar Scaliger, Poetices libri septem (1561)
- Attribution:
primary— a named author, work and year this catalogue stands behind - Checkability:
self— decidable from the text and its parameters alone - Attested:
author-stated— the originator set this rule down
Details¶
- Kind: both
- Languages: en, de
- Requires:
tokens,syllables.heuristic,stress - Deterministic: yes
- In other languages: Proteusvers (de), Vers protée (fr)
Notes¶
Harsdörffer states 39,916,800 permutations for an eleven-word line, which is 11! exactly, and Leibniz takes the figure up in De Arte Combinatoria (1666). It is one of the few counts in this field that can be recomputed from the elements and comes out right. The scanning counts are a different matter: for Bauhusius's hexameter to the Virgin, Puteanus printed 1,022 in 1617, Prestet 2,196 in 1675, Wallis 3,096 in 1685, Leibniz 2,580 in 1686, Bernoulli 3,312 in 1692. They disagree over the ruleset, not the arithmetic, which is why the ruleset is a parameter here and the count a metric rather than a number this row asserts. Knuth gives the history in The Art of Computer Programming 7.2.1.7.
Prompt hint¶
Write a line whose words can be reordered freely while the metre still holds.
Parameters¶
| Name | Type | Default | Description |
|---|---|---|---|
max_words |
integer | 9 |
Refuse a line longer than this rather than search it. |
metre |
string | hexameter |
Which measure the permutations must hold: hexameter, iambic_pentameter, iambic_tetrameter, trochaic_tetrameter. |
minimum |
integer | 2 |
How many valid orderings the line must admit, itself included. |
Examples¶
pentameter-that-permutes¶
en — this text satisfies the procedure.
the cat can see the moon above the tree
Parameters: metre='iambic_pentameter'
Source: constructed example; the same line the iambic_pentameter fixture uses, whose nine words admit 201,600 orderings that also scan
hexameter-tiled-from-known-stress¶
en — this text satisfies the procedure.
murmuring beautiful murmuring wonderful murmuring forest
Source: constructed example; six words of known stress filling the hexameter, the measure the whole tradition argues over. 120 of the 720 orderings scan.
scans-but-does-not-permute-enough¶
en — this text does not satisfy the procedure.
remember the beloved silver sea
Parameters: metre='iambic_pentameter', minimum=9
Source: constructed counterexample; the line holds the metre and admits eight orderings that do, and is asked for nine. Scores 0.5 rather than 0 because the two conditions are reported separately and a writer can fix them separately.
does-not-scan-at-all¶
en — this text does not satisfy the procedure.
the cat sat on the mat
Source: constructed counterexample
more-than-one-line¶
en — this text does not satisfy the procedure.
the cat can see the moon above the tree
the dog will run across the field today
Parameters: metre='iambic_pentameter'
Source: constructed counterexample; a proteus verse is one line, and scanning the second against the first's permutations would report a fault that is not there
voss-odyssee¶
de — this text satisfies the procedure.
Sage mir, Muse, die Taten des vielgewanderten Mannes
Source: Johann Heinrich Voß, tr., Homers Odüssee (1781), opening line. Eight words, 1,728 of whose 40,320 orderings still scan.
deutscher-blankvers¶
de — this text satisfies the procedure.
der Wind bewegt die Blätter in der Nacht
Parameters: metre='iambic_pentameter'
Source: constructed example; the German Blankvers under permutation
zu-kurz¶
de — this text does not satisfy the procedure.
die Katze schläft
Source: constructed counterexample