Why Reed-Kellogg diagrams?
The question is absolutely valid. There are also other ways to represent syntax structures.
Chomsky phrase
marker and it's variations are extensively used to describe the syntax.
Another good grammar is Tesnière
dependency grammar.
There are also other types of grammars.
The question is absolutely important because the chosen syntax is the foundation
for the syntax and semantic processing. Grammar implementation, which translates
sequence of lexemes into a syntax graph, is inevitably built around syntax
and it inherits syntax properties.
If you see a tree structure behind classical Reed-Kellogg diagram it reveals you
its natural elegance and full power. It's amazing, what a great job Alonzo Reed
and Brainerd Kellogg did in 1877 for modern computational linguistic.
Reed-Kellogg diagramming is a standard
Reed-Kellogg grammar is broadly used to represent syntax of
English sentence. It also stays stable for more than a century. That makes Reed-Kellogg
a standard post factum. Strange enough linguists didn't agree on a
syntax standard. There are no ISO or w3org specs for syntax. It hinders
computational linguistic significantly because any, even not perfect standard is
better than nothing; but it is the current situation unfortunately. Among
well-known syntaxes Reed-Kellogg looks more standard than the
others.
Reed-Kellogg syntax is simple
It describes the incredible diversity of English sentence with very few diagram
structures. Once you've learned the structures you can describe any possible sentence.
Reed-Kellogg diagram is good for humans
Reed-Kellogg schema is well known and has large community.
Success of Reed-Kellogg diagramming is probably explained by the fact that
diagram organizes the sentence into a logical structure which is easy for people
to understand.
Reed-Kellogg tree is good for computers
Modern computers are perfectly capable to handle any currently known syntax
graphs but tree structure gives better performance and makes processing straightforward.
It is relatively easy to perform operations on a tree graph. Comparison,
sorting, searching for sub-graphs, finding the differences, matching similar
parts and transformations are fast and easy with a tree.
Once sentence is diagrammed, neither word nor leaf order is important.
It is another great advantage of Reed-Kellogg system, because it significantly simplifies syntax processing for computer.
This fact, for example, allows simple normalization of Reed-Kellogg graphs and gives huge performance gain for operations like search.
When changing leaf order on a graph changes meaning of the sentence, computer programs have to do more work.
Reed-Kellogg diagram is good for any language
Although Reed-Kellogg was initially designed for English it is applicable for any
language with a syntax, isomorphic to a tree graph.
If required, Reed-Kellogg can be extended to other languages by adding new kinds of syntax
roles and structures.
Reed-Kellogg is a complete syntax representation
Reed-Kellogg diagram is complete and ready for semantic processing. For example,
Reed-Kellogg doesn't require shallow syntax and deep syntax.
It fully describes syntax structure of an utterance and has its own value add.
Reed-Kellogg syntax diagram is clearly decoupled from lexical and semantic representations.
It doesn't require words to describe syntax. For example, all the words can be erased from a
graph without loss of syntax information. Such pure syntax
(without words) has neither lexicon nor semantic information.
Reed-Kellogg is proven and reliable
Reed-Kellogg is live since 1877 and tested by many people. Great quality
assurance!