关于《数学核心》中整数、有理数和实数特殊记法的技术咨询

Hey Dimitris,

Great question! I’ve run into a handful of older math textbooks that use non-standard notation for number sets like integers, rationals, and reals—so this isn’t just a one-off quirk of Moakes’ 1964 book.

Here’s some context that might help:

• Back in the mid-20th century, the now-universal blackboard-bold notation (ℤ for integers, ℚ for rationals, ℝ for reals) hadn’t fully solidified as the standard. Many authors leaned into their own shorthand: some used plain uppercase letters, others boldface (Z, Q, R), or even other niche symbols that feel odd to modern readers.
• Moakes’ notation is likely a holdover from pre-standardization textbook conventions, especially since his book was framing "modern" math at a time when those conventions were still being debated and adopted widely.
• You can spot similar quirks in other 1950s-1960s introductory math texts—authors like E.T. Bell or early editions of set theory-focused books often had their own takes on notation before the community settled on the symbols we use today.

If you’re cross-referencing content, a quick check of the book’s glossary (nearly all older math texts included one) will always clarify exactly what each symbol refers to, since consistency was looser back then.

Hope that clears things up!

备注：内容来源于stack exchange，提问作者Dimitris