# Cauchy Mean Theorem

Formalized Mathematics (2014)

- Volume: 22, Issue: 2, page 157-166
- ISSN: 1426-2630

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topAdam Grabowski. "Cauchy Mean Theorem." Formalized Mathematics 22.2 (2014): 157-166. <http://eudml.org/doc/268819>.

@article{AdamGrabowski2014,

abstract = {The purpose of this paper was to prove formally, using the Mizar language, Arithmetic Mean/Geometric Mean theorem known maybe better under the name of AM-GM inequality or Cauchy mean theorem. It states that the arithmetic mean of a list of a non-negative real numbers is greater than or equal to the geometric mean of the same list. The formalization was tempting for at least two reasons: one of them, perhaps the strongest, was that the proof of this theorem seemed to be relatively easy to formalize (e.g. the weaker variant of this was proven in [13]). Also Jensen’s inequality is already present in the Mizar Mathematical Library. We were impressed by the beauty and elegance of the simple proof by induction and so we decided to follow this specific way. The proof follows similar lines as that written in Isabelle [18]; the comparison of both could be really interesting as it seems that in both systems the number of lines needed to prove this are really close. This theorem is item #38 from the “Formalizing 100 Theorems” list maintained by Freek Wiedijk at http://www.cs.ru.nl/F.Wiedijk/100/.},

author = {Adam Grabowski},

journal = {Formalized Mathematics},

keywords = {geometric mean; arithmetic mean; AM-GM inequality; Cauchy mean theorem},

language = {eng},

number = {2},

pages = {157-166},

title = {Cauchy Mean Theorem},

url = {http://eudml.org/doc/268819},

volume = {22},

year = {2014},

}

TY - JOUR

AU - Adam Grabowski

TI - Cauchy Mean Theorem

JO - Formalized Mathematics

PY - 2014

VL - 22

IS - 2

SP - 157

EP - 166

AB - The purpose of this paper was to prove formally, using the Mizar language, Arithmetic Mean/Geometric Mean theorem known maybe better under the name of AM-GM inequality or Cauchy mean theorem. It states that the arithmetic mean of a list of a non-negative real numbers is greater than or equal to the geometric mean of the same list. The formalization was tempting for at least two reasons: one of them, perhaps the strongest, was that the proof of this theorem seemed to be relatively easy to formalize (e.g. the weaker variant of this was proven in [13]). Also Jensen’s inequality is already present in the Mizar Mathematical Library. We were impressed by the beauty and elegance of the simple proof by induction and so we decided to follow this specific way. The proof follows similar lines as that written in Isabelle [18]; the comparison of both could be really interesting as it seems that in both systems the number of lines needed to prove this are really close. This theorem is item #38 from the “Formalizing 100 Theorems” list maintained by Freek Wiedijk at http://www.cs.ru.nl/F.Wiedijk/100/.

LA - eng

KW - geometric mean; arithmetic mean; AM-GM inequality; Cauchy mean theorem

UR - http://eudml.org/doc/268819

ER -

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