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Glyph for U+22A5
Source: Noto Sans Math

U+22A5 Up Tack

U+22A5 was added in Unicode version 1.1 in 1993. It belongs to the block U+2200 to U+22FF Mathematical Operators 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 base and bottom.

The glyph is not a composition. Its width in East Asian texts is determined by its context. It can be displayed wide or narrow. In bidirectional text it acts as Other Neutral. When changing direction it is not mirrored. If its East Asian Width is “narrow”, U+22A5 forms a word with similar characters, which prevents a line break inside it. Otherwise it allows line breaks around it, except in some numeric contexts. The glyph can be confused with one other glyph.

The CLDR project calls this character “up tack” for use in screen reading software. It assigns these additional labels, e.g. for search in emoji pickers: eet, falsum, tack.

The Wikipedia has the following information about this codepoint:

The up tack or falsum (, ot in LaTeX, U+22A5 in Unicode) is a constant symbol used to represent:

  • The truth value 'false', or a logical constant denoting a proposition in logic that is always false (often called "falsum" or "absurdum").
  • The bottom element in wheel theory and lattice theory, which also represents absurdum when used for logical semantics
  • The bottom type in type theory, which is the bottom element in the subtype relation. This may coincide with the empty type, which represents absurdum under the Curry–Howard correspondence
  • The "undefined value" in quantum physics interpretations that reject counterfactual definiteness, as in (r0,⊥)

as well as

  • Mixed radix decoding in the APL programming language

The glyph of the up tack appears as an upside-down tee symbol, and as such is sometimes called eet (the word "tee" in reverse). Tee plays a complementary or dual role in many of these theories.

The similar-looking perpendicular symbol (, perp in LaTeX, U+27C2 in Unicode) is a binary relation symbol used to represent:

  • Perpendicularity of lines in geometry
  • Orthogonality in linear algebra
  • Independence of random variables in probability theory
  • Coprimality in number theory

The double tack up symbol (, U+2AEB in Unicode) is a binary relation symbol used to represent:

  • Conditional independence of random variables in probability theory

Representations

System Representation
8869
UTF-8 E2 8A A5
UTF-16 22 A5
UTF-32 00 00 22 A5
URL-Quoted %E2%8A%A5
HTML hex reference ⊥
Wrong windows-1252 Mojibake ⊥
HTML named entity ⊥
HTML named entity ⊥
HTML named entity ⊥
HTML named entity ⊥
alias base
alias bottom
Encoding: EUC-KR (hex bytes) A1 D1
Encoding: JIS0208 (hex bytes) A2 DD
Encoding: JIS0208 (hex bytes) AD F6
LATEX \perp
Adobe Glyph List perpendicular
digraph -T

Related Characters

Confusables

Elsewhere

Complete Record

Property Value
Age (age) 1.1 (1993)
Unicode Name (na) UP TACK
Unicode 1 Name (na1)
Block (blk) Mathematical Operators
General Category (gc) Math Symbol
Script (sc) Common
Bidirectional Category (bc) Other Neutral
Combining Class (ccc) Not Reordered
Decomposition Type (dt) none
Decomposition Mapping (dm) Glyph for U+22A5 Up Tack
Lowercase (Lower)
Simple Lowercase Mapping (slc) Glyph for U+22A5 Up Tack
Lowercase Mapping (lc) Glyph for U+22A5 Up Tack
Uppercase (Upper)
Simple Uppercase Mapping (suc) Glyph for U+22A5 Up Tack
Uppercase Mapping (uc) Glyph for U+22A5 Up Tack
Simple Titlecase Mapping (stc) Glyph for U+22A5 Up Tack
Titlecase Mapping (tc) Glyph for U+22A5 Up Tack
Case Folding (cf) Glyph for U+22A5 Up Tack
ASCII Hex Digit (AHex)
Alphabetic (Alpha)
Bidi Control (Bidi_C)
Bidi Mirrored (Bidi_M)
Composition Exclusion (CE)
Case Ignorable (CI)
Changes When Casefolded (CWCF)
Changes When Casemapped (CWCM)
Changes When NFKC Casefolded (CWKCF)
Changes When Lowercased (CWL)
Changes When Titlecased (CWT)
Changes When Uppercased (CWU)
Cased (Cased)
Full Composition Exclusion (Comp_Ex)
Default Ignorable Code Point (DI)
Dash (Dash)
Deprecated (Dep)
Diacritic (Dia)
Emoji Modifier Base (EBase)
Emoji Component (EComp)
Emoji Modifier (EMod)
Emoji Presentation (EPres)
Emoji (Emoji)
Extender (Ext)
Extended Pictographic (ExtPict)
FC NFKC Closure (FC_NFKC) Glyph for U+22A5 Up Tack
Grapheme Cluster Break (GCB) Any
Grapheme Base (Gr_Base)
Grapheme Extend (Gr_Ext)
Grapheme Link (Gr_Link)
Hex Digit (Hex)
Hyphen (Hyphen)
ID Continue (IDC)
ID Start (IDS)
IDS Binary Operator (IDSB)
IDS Trinary Operator and (IDST)
IDSU (IDSU) 0
ID_Compat_Math_Continue (ID_Compat_Math_Continue) 0
ID_Compat_Math_Start (ID_Compat_Math_Start) 0
Ideographic (Ideo)
InCB (InCB) None
Indic Mantra Category (InMC)
Indic Positional Category (InPC) NA
Indic Syllabic Category (InSC) Other
Jamo Short Name (JSN)
Join Control (Join_C)
Logical Order Exception (LOE)
Math (Math)
Noncharacter Code Point (NChar)
NFC Quick Check (NFC_QC) Yes
NFD Quick Check (NFD_QC) Yes
NFKC Casefold (NFKC_CF) Glyph for U+22A5 Up Tack
NFKC Quick Check (NFKC_QC) Yes
NFKC_SCF (NFKC_SCF) Glyph for U+22A5 Up Tack
NFKD Quick Check (NFKD_QC) Yes
Other Alphabetic (OAlpha)
Other Default Ignorable Code Point (ODI)
Other Grapheme Extend (OGr_Ext)
Other ID Continue (OIDC)
Other ID Start (OIDS)
Other Lowercase (OLower)
Other Math (OMath)
Other Uppercase (OUpper)
Prepended Concatenation Mark (PCM)
Pattern Syntax (Pat_Syn)
Pattern White Space (Pat_WS)
Quotation Mark (QMark)
Regional Indicator (RI)
Radical (Radical)
Sentence Break (SB) Other
Soft Dotted (SD)
Sentence Terminal (STerm)
Terminal Punctuation (Term)
Unified Ideograph (UIdeo)
Variation Selector (VS)
Word Break (WB) Other
White Space (WSpace)
XID Continue (XIDC)
XID Start (XIDS)
Expands On NFC (XO_NFC)
Expands On NFD (XO_NFD)
Expands On NFKC (XO_NFKC)
Expands On NFKD (XO_NFKD)
Bidi Paired Bracket (bpb) Glyph for U+22A5 Up Tack
Bidi Paired Bracket Type (bpt) None
East Asian Width (ea) ambiguous
Hangul Syllable Type (hst) Not Applicable
ISO 10646 Comment (isc)
Joining Group (jg) No_Joining_Group
Joining Type (jt) Non Joining
Line Break (lb) Ambiguous (Alphabetic or Ideographic)
Numeric Type (nt) none
Numeric Value (nv) not a number
Simple Case Folding (scf) Glyph for U+22A5 Up Tack
Script Extension (scx)
Vertical Orientation (vo) R