Editing Xi (letter) (section)

==== Other uses ====
* Propositional variables in some philosophical works, first found in Wittgenstein's [[Tractatus Logico-Philosophicus|Tractatus]]
* [[Extent of reaction]], a concept in [[physical chemistry]]<ref>IUPAC Gold Book Entry: [http://goldbook.iupac.org/E02283.html "Extent of Reaction"] {{webarchive |url=https://web.archive.org/web/20120629101118/http://goldbook.iupac.org/E02283.html |date=June 29, 2012 }}</ref> used often in [[chemical engineering]] kinetics and [[thermochemistry]]
* Unknown [[stereochemistry]] or [[stereocentre]] configuration in a planar [[ring (chemistry)|ring system]] in [[organic chemistry]],<ref name="BuckinghamCooper2015">{{cite book|first1=John|last1=Buckingham|first2=Caroline M.|last2=Cooper|first3=Rupert|last3=Purchase|title=Natural Products Desk Reference|url=https://books.google.com/books?id=n4zwCgAAQBAJ&pg=PA53|date=18 November 2015|publisher=CRC Press|isbn=978-1-4398-7362-5|pages=53–}}</ref> as well as uppercase Xi for unknown ''R''/''S''/''E''/''Z'' configuration in general<ref>{{cite book|title=Nomenclature of Organic Chemistry: IUPAC Recommendations and Preferred Names|year=2014|pages=1159–1160|publisher=Royal Society of Chemistry |isbn=9780854041824|url=https://books.google.com/books?id=4USgAgAAQBAJ&pg=1160|access-date=11 September 2017}}</ref>
* One of the two different polypeptide chains of the human embryonic [[hemoglobin]] types Hb-Portland (ξ<sub>2</sub>γ<sub>2</sub>) and Hb-Gower I (ξ<sub>2</sub>ε<sub>2</sub>)
* A parameter denoted as [[warped time]] used to derive the equations for homogeneous [[azeotropic distillation]]
* State Price Density in [[mathematical finance]]
* The information vector in the [[Information Filter]], [[GraphSLAM]], and a number of other algorithms used for [[robot localization]] and [[robotic mapping]].
* Used in [[Support-vector machine|Support Vector machines]] in cases where the data is not [[Linear separability|linearly separable]].
* Used in [[Microelectronics]] to represent the distance from a [[p-n junction]] to a point in the [[depletion region]] where the [[electric field]] is strongest.