<?xml version="1.0" encoding="UTF-8"?><!DOCTYPE article  PUBLIC "-//NLM//DTD Journal Publishing DTD v3.0 20080202//EN" "http://dtd.nlm.nih.gov/publishing/3.0/journalpublishing3.dtd"><article xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink" dtd-version="3.0" xml:lang="en" article-type="research article"><front><journal-meta><journal-id journal-id-type="publisher-id">NS</journal-id><journal-title-group><journal-title>Natural Science</journal-title></journal-title-group><issn pub-type="epub">2150-4091</issn><publisher><publisher-name>Scientific Research Publishing</publisher-name></publisher></journal-meta><article-meta><article-id pub-id-type="doi">10.4236/ns.2020.129055</article-id><article-id pub-id-type="publisher-id">NS-102835</article-id><article-categories><subj-group subj-group-type="heading"><subject>Articles</subject></subj-group><subj-group subj-group-type="Discipline-v2"><subject>Biomedical&amp;Life Sciences</subject><subject> Chemistry&amp;Materials Science</subject><subject> Earth&amp;Environmental Sciences</subject><subject> Medicine&amp;Healthcare</subject><subject> Physics&amp;Mathematics</subject></subj-group></article-categories><title-group><article-title>
 
 
  The Significant and Profound Impacts of Chou’s Invariance Theorem
 
</article-title></title-group><contrib-group><contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Kuo-Chen</surname><given-names>Chou</given-names></name><xref ref-type="aff" rid="aff1"><sub>1</sub></xref></contrib></contrib-group><aff id="aff1"><label>1</label><addr-line>Gordon Life Science Institute, Boston, MA, USA</addr-line></aff><pub-date pub-type="epub"><day>09</day><month>09</month><year>2020</year></pub-date><volume>12</volume><issue>09</issue><fpage>659</fpage><lpage>660</lpage><history><date date-type="received"><day>2,</day>	<month>September</month>	<year>2020</year></date><date date-type="rev-recd"><day>12,</day>	<month>September</month>	<year>2020</year>	</date><date date-type="accepted"><day>15,</day>	<month>September</month>	<year>2020</year></date></history><permissions><copyright-statement>&#169; Copyright  2014 by authors and Scientific Research Publishing Inc. </copyright-statement><copyright-year>2014</copyright-year><license><license-p>This work is licensed under the Creative Commons Attribution International License (CC BY). http://creativecommons.org/licenses/by/4.0/</license-p></license></permissions><abstract><p>
 
 
  In this short review paper, the significant and profound impacts of the Chou’s “invariance theorem” have been briefly presented with crystal clear convincingness.
 
</p></abstract><kwd-group><kwd>Invariance Theorem</kwd><kwd> Mahalanobis Distance</kwd><kwd> Significant Impacts</kwd><kwd> Profound Impacts</kwd></kwd-group></article-meta></front><body><sec id="s1"><title>CONFLICTS OF INTEREST</title><p>The author declares no conflicts of interest regarding the publication of this paper.</p></sec><sec id="s2"><title>REFERENCES</title></sec></body><back><ref-list><title>References</title><ref id="scirp.102835-ref1"><label>1</label><mixed-citation publication-type="other" xlink:type="simple">Chou, K.C. (1995) A Novel Approach to Predicting Protein Structural Classes in a (20-1)-D Amino Acid Composition Space. Proteins: Structure, Function &amp; Genetics, 21, 319-344. https://doi.org/10.1002/prot.340210406</mixed-citation></ref><ref id="scirp.102835-ref2"><label>2</label><mixed-citation publication-type="other" xlink:type="simple">Mahalanobis, P.C. (1936) On the Generalized Distance in Statistics. Proceedings of the National Academy of Sciences, India, 2, 49-55.</mixed-citation></ref><ref id="scirp.102835-ref3"><label>3</label><mixed-citation publication-type="book" xlink:type="simple">Pillai, K.C.S. and Mahalanobis, D. (1985) Encyclopedia of Statistical Sciences. In: Kotz, S. and Johnson, N.L., Eds., John Wiley &amp; Sons. (This Reference Also Presents a Brief Biography of Mahalanobis Who Was a Man of Great Originality and Who Made Considerable Contributions to Statistics, New York, 176-181.)</mixed-citation></ref><ref id="scirp.102835-ref4"><label>4</label><mixed-citation publication-type="other" xlink:type="simple">Liu, W. and Chou, K.C. (1998) Prediction of Protein Structural Classes by Modified Mahalanobis Discriminant Algorithm. Journal of Protein Chemistry, 17, 209-217. https://doi.org/10.1023/A:1022576400291</mixed-citation></ref><ref id="scirp.102835-ref5"><label>5</label><mixed-citation publication-type="other" xlink:type="simple">Lin, H. and Li, Q.Z. (2007) Predicting Conotoxin Superfamily and Family by Using Pseudo Amino Acid Composition and Modified Mahalanobis Discriminant. Biochemical and Biophysical Research Communications, 354, 548-551. https://doi.org/10.1016/j.bbrc.2007.01.011</mixed-citation></ref><ref id="scirp.102835-ref6"><label>6</label><mixed-citation publication-type="other" xlink:type="simple">Lin, H. (2008) The Modified Mahalanobis Discriminant for Predicting Outer Membrane Proteins by Using Chou’s Pseudo Amino Acid Composition. Journal of Theoretical Biology, 252, 350-356.  
https://doi.org/10.1016/j.jtbi.2008.02.004</mixed-citation></ref><ref id="scirp.102835-ref7"><label>7</label><mixed-citation publication-type="other" xlink:type="simple">Ding, H., Liu, L., Guo, F.B., Huang, J. and Lin, H. (2011) Identify Golgi Protein Types with Modified Mahalanobis Discriminant Algorithm and Pseudo Amino Acid Composition. Protein &amp; Peptide Letters, 18, 58-63.  
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