say what the music theory book is about

content/books/the-algorithmic-foundations-of-music-theory/_index.md

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+## About the book
+
+Music theory is full of names, patterns and conventions, and most of us learn
+them as rules to memorize. This book works out where they come from.
+
+Take a simple example. In C major, the chord built on D is minor. You can
+memorize that, or you can take every other note of the scale starting from D,
+which gives D, F, A, and look at the intervals between them. Once you know how
+that construction works, you can repeat it on any degree, in any key. One
+procedure explains a whole family of results.
+
+That is the algorithmic view: state the starting material, state each operation
+applied to it, and follow the steps. Writing them down exposes the assumptions
+a familiar name can hide, and gives you something to test. Change the input,
+run the procedure, and compare the result with what you hear.
+
+Not everything reduces to a construction. A chord's notes don't tell you what
+it is doing in a phrase, and deciding where a melody should go involves style,
+context and taste. When the book models that kind of behavior, it says which
+relationships it keeps and which it leaves out.
+
+The book grew out of years of music notebooks and a software project,
+[go-harmony](https://github.com/poolpOrg/go-harmony), a music-theory engine
+that builds intervals, scales, chords and progressions. Writing that engine
+meant spelling out everything I "just knew", and those explanations became
+this book.
+
+## What's inside
+
+The book concentrates on Western tonal theory and jazz, starting from sound and
+time and building up to the relationships that organize notes into music.
+
+- *Foundations*: sound, time, rhythm and perception; notes, intervals, tuning
+  and temperament; scales, modes and chords; staff notation, analysis systems
+  and MIDI.
+- *Building harmony and melody*: harmony and secondary chords, texture, voice
+  leading, cadences and phrase structure, melodic development, common
+  progressions.
+- *Advanced harmony*: extended chords, substitutions and reharmonization,
+  Neapolitan and augmented sixth chords, modulation, pitch-class sets.
+- *Rhythm and groove*: rhythmic placement, polyrhythm and cross-rhythm.
+- *Form and application*: form and structure, a worked analysis,
+  improvisation, composition and ear training.
+
+Chapters come with exercises and worked solutions. A glossary and appendices
+of Python listings at the back turn the procedures into code you can run.
+
+## Who it's for
+
+You can come to it from music, from programming, or from curiosity about how
+the two meet. No prior music theory is assumed. The math is introduced where it
+is used: ratios, logarithms and a little modular arithmetic. The Python
+listings make the procedures concrete, but you can follow the main text without
+running them.