# Manin obstruction

From Encyclopedia of Mathematics

*Brauer–Manin obstruction*

An invariant attached to a geometric object $X$ which measures the failure of the Hasse principle for $X$: that is, if the obstruction is non-trivial, then $X$ may have points over all local fields but not over a global field.

For abelian varieties the Manin obstruction is just the Tate-Shafarevich group and fully accounts for the failure of the local-to-global principle. There are however examples, due to Skorobogatov, of varieties with trivial Manin obstruction which have points everywhere locally and yet no global points.

## References

- Serge Lang
*Survey of Diophantine geometry*Springer-Verlag (1997) ISBN 3-540-61223-8. Zbl 0869.11051. pp.250–258. - Alexei Skorobogatov "Beyond the Manin obstruction" (with Appendix A by S. Siksek: 4-descent).
*Inventiones Mathematicae***135**no.2 (1999) 399–424. DOI 10.1007/s002220050291. Zbl 0951.14013. - Alexei Skorobogatov
*Torsors and rational points*Cambridge Tracts in Mathematics**144**Cambridge University Press (2001) ISBN 0-521-80237-7 Zbl 0972.14015. pp.1–7,112.

**How to Cite This Entry:**

Manin obstruction.

*Encyclopedia of Mathematics.*URL: http://encyclopediaofmath.org/index.php?title=Manin_obstruction&oldid=37487