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Bulletin of the American Mathematical Society

The Bulletin publishes expository articles on contemporary mathematical research, written in a way that gives insight to mathematicians who may not be experts in the particular topic. The Bulletin also publishes reviews of selected books in mathematics and short articles in the Mathematical Perspectives section, both by invitation only.

ISSN 1088-9485 (online) ISSN 0273-0979 (print)

The 2020 MCQ for Bulletin of the American Mathematical Society is 0.84.

What is MCQ? The Mathematical Citation Quotient (MCQ) measures journal impact by looking at citations over a five-year period. Subscribers to MathSciNet may click through for more detailed information.


Whitney’s extension problems and interpolation of data
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by Charles Fefferman PDF
Bull. Amer. Math. Soc. 46 (2009), 207-220 Request permission


Given a function $f: E \rightarrow {\mathbb {R}}$ with $E \subset {\mathbb {R}}^n$, we explain how to decide whether $f$ extends to a $C^m$ function $F$ on ${\mathbb {R}}^n$. If $E$ is finite, then one can efficiently compute an $F$ as above, whose $C^m$ norm has the least possible order of magnitude (joint work with B. Klartag).
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Additional Information
  • Charles Fefferman
  • Affiliation: Department of Mathematics, Princeton University, Fine Hall, Washington Road, Princeton, New Jersey 08544
  • MR Author ID: 65640
  • Email:
  • Received by editor(s): September 2, 2008
  • Published electronically: November 24, 2008
  • Additional Notes: The author was supported by grants DMS-0601025 and ONR-N00014-08-1-0678.
  • © Copyright 2008 American Mathematical Society
    The copyright for this article reverts to public domain 28 years after publication.
  • Journal: Bull. Amer. Math. Soc. 46 (2009), 207-220
  • MSC (2000): Primary 49K24, 52A35
  • DOI:
  • MathSciNet review: 2476412