The topic paragraph states the collection of ideas to be explained in subsequent paragraphs, and tells the reader why he should pay attention to the subsequent definitions, details, etc.
The topic sentence summarizes the point of the paragraph in one sentence. The remaining sentences merely elaborate on the topic sentence. There should be NO sentence in a paragraph that does NOT relate to the topic sentence.
This linking, sometimes called spiraling, provides transition between paragraph, makes it hard for the reader to stop reading, and thus makes the section or chapter read smoothly.
Also, do not locate the definition pages before its first use. Finally, avoid defining notation, mnemonics, or acronyms if there are used two or fewer times.