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For questions in Mathematics Education as a scientific discipline. For more hands-on questions on teaching Mathematics, please use the tag teaching. There is also a Stack Exchange community http://matheducators.stackexchange.com/

64 votes

Real-world applications of mathematics, by arxiv subject area?

math.AC Commutative algebra Reed-Solomon codes (a type of error correction codes based on polynomials over finite fields - this is why CDs and DVDs still work even after being scratched!)
Martin Sleziak's user avatar
46 votes

Real-world applications of mathematics, by arxiv subject area?

math.DG Differential geometry Lie groups are used in robotics (to find the most efficient way to maneuver a robotic arm, for instance). Spherical trigonometry is essential for navigation (a few centu …
Martin Sleziak's user avatar
30 votes

Real-world applications of mathematics, by arxiv subject area?

math.AG Algebraic geometry Elliptic curve cryptography Motion planning: Configuration spaces of robot arms are semi-algebraic sets, and algebraic geometry (especially the Cylindrical Algebraic Decomp …
Martin Sleziak's user avatar
31 votes

Real-world applications of mathematics, by arxiv subject area?

math.ST Statistics almost everywhere Accurate polling Fraud detection: whether financial (e.g. via Benford's law) or voter fraud. Used in the world of finance, economics and gambling on a daily basis …
Martin Sleziak's user avatar
21 votes

Real-world applications of mathematics, by arxiv subject area?

math.NA Numerical analysis Linear programming algorithms are used in compressed sensing, which is now being used in MRI and imaging to increase resolution and/or decrease the number of measurements r …
Martin Sleziak's user avatar
6 votes

Real-world applications of mathematics, by arxiv subject area?

math.GM General Mathematics The cosmic distance ladder is largely built using elementary geometry (although for some legs of the ladder, more advanced mathematics, e.g. relativity and probability, pl …
Martin Sleziak's user avatar
380 votes

Examples of common false beliefs in mathematics

The closure of the open ball of radius $r$ in a metric space, is the closed ball of radius $r$ in that metric space. In a somewhat related spirit: the boundary of a subset of (say) Euclidean space ha …
Semiclassical's user avatar
103 votes

Examples of common false beliefs in mathematics

In order to show that a polynomial $P \in F[x_1,\ldots,x_n]$ vanishes, it suffices to show that $P(x_1,\ldots,x_n) = 0$ for all $x_1,\ldots,x_n \in F$. True in infinite fields, but very false for sma …
Michael Hardy's user avatar
88 votes

Examples of common false beliefs in mathematics

This is perhaps a misunderstood definition rather than a false belief, but: "A subnet of a net $( x_\alpha )_{\alpha \in A}$ takes the form $( x_\alpha )_{\alpha \in B}$ for some subset $B$ of $A$. …
Whosyourjay's user avatar
207 votes

Examples of common false beliefs in mathematics

Some false beliefs in linear algebra: If two operators or matrices $A$, $B$ commute, then they are simultaneously diagonalisable. (Of course, this overlooks the obvious necessary condition that each …
Mohsen Shahriari's user avatar
17 votes

Real-world applications of mathematics, by arxiv subject area?

math.SP Spectral theory Spectroscopy (of course) To avoid bridge collapse, knowing where the resonant frequencies are is extremely important. :-) Shape and model recognition Network analysis and sec …
Alexandre's user avatar
141 votes
Accepted

Is the boundary $\partial S$ analogous to a derivative?

The surface area $|\partial S|$ of a (bounded, smooth) body $S$ is the derivative of the volume $|S_r|$ of the $r$-neighbourhoods $S_r$ of $S$ at $r=0$: $$ |\partial S| = \frac{d}{dr} |S_r| |_{r=0}.$ …
kjo's user avatar
  • 113
15 votes

Insightful books about elementary mathematics

If first-order logic counts as "elementary mathematics", then I would like to suggest (the relevant chapters of) "Godel, Escher, Bach", by Douglas Hofstadter. (As an aside: Hofstadter's puzzle of enc …
Terry Tao's user avatar
  • 114k
94 votes
Accepted

Are there proofs that you feel you did not "understand" for a long time?

As an undergraduate, I learned the Sylow theorems in my algebra classes but could never retain either the statement or proof of these theorems in memory except for short periods of time (and in partic …
Terry Tao's user avatar
  • 114k
16 votes

Reference for a nice proof of "undetermined coefficients"

If $L$ has characteristic polynomial $\lambda \mapsto p(\lambda)$, then the conjugated differential operator $e^{-qt} L e^{qt}$ has characteristic polynomial $\lambda \mapsto p(\lambda+q)$. From thi …
Terry Tao's user avatar
  • 114k

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