The Mathematical Symbol "Does Not Precede (⊀)"

Demystifying the "Does Not Precede" Symbol (⊀): A Relational Perspective

In the vast landscape of mathematical notation, the myriad of symbols used can sometimes seem overwhelming. One such symbol, which holds unique significance in order theory and other mathematical contexts, is the "Does Not Precede" notation, represented as ⊀. This article dives into the essence of this symbol, supported by example-driven explanations.

Decoding the ⊀ Symbol

The ⊀ symbol is fundamentally a relational symbol used to denote that a certain element does not precede another in a given order. In order theory, a branch of mathematics that studies binary relations, this symbol communicates the absence of a particular ordering relationship between two elements.

Example 1:

Consider a partially ordered set (poset) of numbers where the ordering is defined by divisibility. In this set, if number \( a \) does not divide number \( b \), then we can express this relation as:

\( a ⊀ b \)

Example 2:

Assume a set of tasks that need to be completed, and there's a partial order that dictates which tasks must be done before others. If task \( X \) does not necessarily have to be completed before task \( Y \), this can be symbolized as:

\( X ⊀ Y \)

The significance of the ⊀ symbol becomes apparent in contexts where the absence of a specific order or precedence between elements is essential to the matter at hand. Like many mathematical symbols, the ⊀ symbol demands an understanding of the underlying structure or set in which it's being used to be fully appreciated.

Mathematical symbol 'Does Not Precede'

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Codes for the ⊀ Symbol

The Symbol
Alt CodeAlt 8832
HTML Code⊀
HTML Entity⊀
CSS Code\2280
Hex Code⊀

How To Insert the ⊀ Symbol

(Method 1) Copy and paste the symbol.

The easiest way to get the ⊀ symbol is to copy and paste it into your document.

Bear in mind that this is a UTF-8 encoded character. It must be encoded as UTF-8 at all stages (copying, replacing, editing, pasting), otherwise it will render as random characters or the dreaded �.

(Method 2) Use the "Alt Code."

If you have a keyboard with a numeric pad, you can use this method. Simply hold down the Alt key and type 8832. When you lift the Alt key, the symbol appears. ("Num Lock" must be on.)

(Method 3) Use the HTML Decimal Code (for webpages).

HTML TextOutput
<b>My symbol: &#8832;</b>My symbol: ⊀

(Method 4) Use the HTML Entity Code (for webpages).

HTML TextOutput
<b>My symbol: &npr;</b>My symbol: ⊀

(Method 5) Use the CSS Code (for webpages).

CSS and HTML TextOutput
span:after {
content: "\2280";}
<span>My symbol:</span>
My symbol: ⊀

(Method 6) Use the HTML Hex Code (for webpages and HTML canvas).

HTML TextOutput
<b>My symbol: &#x2280;</b>My symbol: ⊀
On the assumption that you already have your canvas and the context set up, use the Hex code in the format 0x2280 to place the ⊀ symbol on your canvas. For example:
JavaScript Text
const x = "0x"+"E9"
ctx.fillText(String.fromCodePoint(x), 5, 5);

(Method 7) Use the Unicode (for various, e.g. Microsoft Office, JavaScript, Perl).

The Unicode for ⊀ is U+2280. The important part is the hexadecimal number after the U+, which is used in various formats. For example, in Microsoft Office applications (e.g. Word, PowerPoint), do the following:
[Hold down Alt]
[Press x]

(The 2280 turns into ⊀. Note that you can omit any leading zeros.)
In JavaScript, the syntax is \uXXXX. So, our example would be \u2280. (Note that the format is 4 hexadecimal characters.)
JavaScript TextOutput
let str = "\u2280"
document.write("My symbol: " + str)
My symbol: ⊀