Home U+2190 to U+21FF Arrows
Glyph for U+21A0
Source: Noto Sans Math

U+21A0 RIGHTWARDS TWO HEADED ARROW

U+21A0 was added to Unicode in version 1.1 (1993). It belongs to the block U+2190 to U+21FF Arrows in the U+0000 to U+FFFF Basic Multilingual Plane.

This character is a Math Symbol and is commonly used, that is, in no specific script. The character is also known as z notation total surjection and fast cursor right.

The glyph is not a composition. It has a Neutral East Asian Width. In bidirectional context it acts as Other Neutral and is not mirrored. The glyph can, under circumstances, be confused with 1 other glyphs. In text U+21A0 behaves as Alphabetic regarding line breaks. It has type Other for sentence and Other for word breaks. The Grapheme Cluster Break is Any.

The CLDR project labels this character “rightwards two headed arrow” for use in screen reading software. It assigns additional tags, e.g. for search in emoji pickers: rightwards two headed arrow.

The Wikipedia has the following information about this codepoint:

In mathematics, a surjective function (also known as surjection, or onto function) is a function f that maps an element x to every element y; that is, for every y, there is an x such that f(x) = y. In other words, every element of the function's codomain is the image of at least one element of its domain. It is not required that x be unique; the function f may map one or more elements of X to the same element of Y.

The term surjective and the related terms injective and bijective were introduced by Nicolas Bourbaki, a group of mainly French 20th-century mathematicians who, under this pseudonym, wrote a series of books presenting an exposition of modern advanced mathematics, beginning in 1935. The French word sur means over or above, and relates to the fact that the image of the domain of a surjective function completely covers the function's codomain.

Any function induces a surjection by restricting its codomain to the image of its domain. Every surjective function has a right inverse assuming the axiom of choice, and every function with a right inverse is necessarily a surjection. The composition of surjective functions is always surjective. Any function can be decomposed into a surjection and an injection.

Representations

System Representation
8608
UTF-8 E2 86 A0
UTF-16 21 A0
UTF-32 00 00 21 A0
URL-Quoted %E2%86%A0
HTML-Escape ↠
Wrong windows-1252 Mojibake ↠
HTML-Escape ↠
HTML-Escape ↠
alias z notation total surjection
alias fast cursor right
LATEX \twoheadrightarrow

Related Characters

Confusables

Elsewhere

Complete Record

Property Value
Age 1.1 (1993)
Unicode Name RIGHTWARDS TWO HEADED ARROW
Unicode 1 Name RIGHT TWO HEADED ARROW
Block Arrows
General Category Math Symbol
Script Common
Bidirectional Category Other Neutral
Combining Class Not Reordered
Decomposition Type None
Decomposition Mapping Glyph for U+21A0 Rightwards Two Headed Arrow
Lowercase
Simple Lowercase Mapping Glyph for U+21A0 Rightwards Two Headed Arrow
Lowercase Mapping Glyph for U+21A0 Rightwards Two Headed Arrow
Uppercase
Simple Uppercase Mapping Glyph for U+21A0 Rightwards Two Headed Arrow
Uppercase Mapping Glyph for U+21A0 Rightwards Two Headed Arrow
Simple Titlecase Mapping Glyph for U+21A0 Rightwards Two Headed Arrow
Titlecase Mapping Glyph for U+21A0 Rightwards Two Headed Arrow
Case Folding Glyph for U+21A0 Rightwards Two Headed Arrow
ASCII Hex Digit
Alphabetic
Bidi Control
Bidi Mirrored
Bidi Paired Bracket Glyph for U+21A0 Rightwards Two Headed Arrow
Bidi Paired Bracket Type None
Cased
Composition Exclusion
Case Ignorable
Full Composition Exclusion
Changes When Casefolded
Changes When Casemapped
Changes When NFKC Casefolded
Changes When Lowercased
Changes When Titlecased
Changes When Uppercased
Dash
Deprecated
Default Ignorable Code Point
Diacritic
East Asian Width Neutral
Emoji Modifier Base
Emoji Component
Emoji Modifier
Emoji
Emoji Presentation
Extender
Extended Pictographic
FC NFKC Closure Glyph for U+21A0 Rightwards Two Headed Arrow
Grapheme Cluster Break Any
Grapheme Base
Grapheme Extend
Grapheme Link
Hex Digit
Hangul Syllable Type Not Applicable
Hyphen
ID Continue
Ideographic
ID Start
IDS Binary Operator
IDS Trinary Operator and
Indic Mantra Category
Indic Positional Category NA
Indic Syllabic Category Other
ISO 10646 Comment
Joining Group No_Joining_Group
Join Control
Jamo Short Name
Joining Type Non Joining
Line Break Alphabetic
Logical Order Exception
Math
Noncharacter Code Point
NFC Quick Check Yes
NFD Quick Check Yes
NFKC Casefold Glyph for U+21A0 Rightwards Two Headed Arrow
NFKC Quick Check Yes
NFKD Quick Check Yes
Numeric Type None
Numeric Value not a number
Other Alphabetic
Other Default Ignorable Code Point
Other Grapheme Extend
Other ID Continue
Other ID Start
Other Lowercase
Other Math
Other Uppercase
Pattern Syntax
Pattern White Space
Prepended Concatenation Mark
Quotation Mark
Radical
Regional Indicator
Sentence Break Other
Simple Case Folding Glyph for U+21A0 Rightwards Two Headed Arrow
Script Extension
Soft Dotted
Sentence Terminal
Terminal Punctuation
Unified Ideograph
Vertical Orientation R
Variation Selector
Word Break Other
White Space
XID Continue
XID Start
Expands On NFC
Expands On NFD
Expands On NFKC
Expands On NFKD