## Note on Notation

One reason why people are scared of/hate mathematics is that once people see an expression like

$:A_0(x_1)\cdots A_0(x_n):\ = \sum_{X\subset\{1,...,n\}}\prod_{i\in X}A_+(x_i)\prod_{j\in CX}A_-(x_j)$

they run and hide.  Let us step back for a moment and try to see what’s really going on here, so that we can better understand this fear, and possibly do away with some of it.

The above expression is scary not because the ideas inherently hidden within it are bad or ugly, but rather only because we do not understand the notation of the expression.  In other words, we don’t understand the chosen symbols used to represent the ideas.  It might as well be Egyptian hieroglyphics for all we know.  In fact, math could have been written down in Egyptian hieroglyphics and its logical content would still be exactly the same.  Why is this?  To answer this question, we need to better understand the role that notation plays for us in mathematics.  In doing so, we’ll understand one of the many reasons why math is in fact not so scary.

I’ll begin with a question:

What do I mean when I write down the number 3?

Note that I’m not asking “what is the number 3”, but rather I am asking what the meaning of the symbol “3” is.  This is a subtle but extremely important issue.  The symbol 3 is shorthand notation for the abstract concept of “three” which we keep in our heads.  Thus, when I write down 3 and you read 3, I can know that we’re keeping the same abstract idea in our minds.  In other words, the symbol 3 means nothing without the abstract meaning that we give it.  Moreover, it is simply a shorter, more concise way of keeping track of the abstract notion of “three-ness”.  We could have written any other symbol in its place, and its abstract meaning would be the same.

Let us take an example that is even closer to home.  Consider, for example, the words on this page.  You’re looking at this strange concoction of squiggly and straight lines, interspersed with blank white space, and you’re deriving from it certain meaning.  Simply put, you’re reading.  You’re extracting meaning from the abstract ideas that are represented by a relatively arbitrary mixture of symbols.  Moreover, the meaning derived from these symbols is independent of the symbols themselves, i.e., we could have all agreed to use other symbols and the abstract ideas would be left intact, so long as we agreed on what the symbols meant.  Therein lies the creation of new/different languages!

In addition to representing words (abstract ideas) by symbols on a page, we can define new words based on old words.   In doing so, we can have shorter ways of expressing more and more meaning.  For example, we defined the word “bus” so that we could encapsulate all of the meaning of “bigger version of a car, designed for transporting large amounts of people” without having to always write the whole thing down.  Thus, when you read the word “bus” you automatically associate it with this larger meaning, and the word “bus” is just a convenient abbreviation.  We then can use this word to define a new word, namely “school bus”.  This way we can simply say “school bus” instead of always having to say “bigger version of a car, designed for transporting large amounts of people to and from school”.

Math is no different.  We use symbols to wrap up more and more meaning into less and less writing.  This has no effect on the logical content of a given mathematical statement or equation—notation is simply used so that we humans can communicate mathematics to each other.  Thus, if you can read (which I’m assuming you can since if you can’t you’ll never know that I’m assuming you can) then you are already doing exactly what you were scared to do by looking at the above equation—namely, deriving abstract information from a language designed to capture and emphasize certain ideas.

Here’s a quick way to become less scared of math.  Consider the term “symplectic manifold”.  There is a decent chance the reader has no idea what a symplectic manifold is, and therefore is confused, and therefore is worried that he’ll never understand math, and therefore is scared of math forever, and therefore tries to learn guitar instead, and therefore becomes that guy at parties always playing the guitar and pissing people off.  I’m here to argue that there’s a better way.

As mentioned before, the words “symplectic manifold” are just abbreviations for other constructions, which are in turn abbreviations for other constructions—just like “school bus” (and just like the symbols in the expression at the top of the page—each standing for some larger, well-constructed idea).  In fact, a symplectic manifold is nothing but a differentiable manifold with some additional properties, and a differentiable manifold is nothing but a manifold with some additional properties, and a manifold is nothing but a topological space with some additional properties, and a topological space is nothing but a set with some additional properties, and we study sets in the second lesson of this site, requiring no further background!  Of course I’m not trying to say that a symplectic manifold is a particularly easy thing to study, but I am saying that there’s nothing to be inherently scared of.  If you can make it through lessons 1 and 2 (and lesson 1 is hardly even a lesson), then you’re well on your way to learning what a symplectic manifold is.  BOOM.  All of mathematics is now at your fingertips…

Lover of math, and lover of teaching it.
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### 19 Responses to Note on Notation

1. Kaeros says:

Your way of expressing what math is, is great! Thank you for taking your time to write this. 🙂

• quantumlotus says:

Thanks! And it’s really my pleasure 🙂

2. Rory says:

Absolutely love the logic behind (and in) this post! Great site and great work, keep it up!

• Thanks! Glad you like it, and I’ll definitely try to keep it up 🙂

3. Wales says:

You, whoever you are, are a wonderful human being.

• haha I’ll take that as a sign that you like the site, in which case I’m glad!

4. Walter says:

wow! I’m having goose bumps reading … phew let me try to hold till the end

5. Kat says:

Oh God, thank you. I already feel relieved, which is amazing after looking at that horror-inducing notation.

6. Anonymous says:

Very good post. I am trying to get the intuition behind math, how things are constructed and this post is very useful.

7. Marco Lucas says:

I really like thos “new” type of teaching math. I believe world will evolve trough this way. Thank you very much!

8. Sourabh Kashyap says:

Great work , unique work.
Ur doing is like the doing of Buddha , Nagarjun in the sense that it carry unmenifested possibilities.

People like u takes birth once in the lifetime of universe.

• Wow, thanks for the kind words! I’m glad to hear that you’re enjoying the site, and I hope you continue to do so!

9. Thank you for creating the site! Loving the premise and content so far. Incredibly excited to see what is ahead.

• Awesome! Glad you like the site and thanks for letting me know 🙂 sorry for my lateness on replying, the last couple months have just been insanity for me, but now I’m back in action and will be adding to the site soon. I hope you continue to enjoy!

10. Staedtler Chan says:

You fantastic, fabulous person, you!