General notation

symbol	meaning	first
symbol	meaning	first
$a:=b$	$a$ is defined to be $b$	chapter 1
$a\equiv b$	judgmental equality in running mathematics	chapter 26
${\lambda }^{\to }$	simply typed lambda calculus	chapter 2
$Rule$	name of an inference rule	chapter 1

Chapter files define no macros locally. Globally fixed notation is exported by dttbook.sty; part-wide signatures and chapter-local borrowed notation are admitted by the semantic registry and introduced at the point of first use. A raw symbol is not accepted merely because TeX can print it.