Overview[ edit ] Definitions of complexity often depend on the concept of a confidential " system " — a set of parts or elements that have relationships among them differentiated from relationships with other elements outside the relational regime. Many definitions tend to postulate or assume that complexity expresses a condition of numerous elements in a system and numerous forms of relationships among the elements. However, what one sees as complex and what one sees as simple is relative and changes with time. Warren Weaver posited in two forms of complexity:
His father William started an experimental school in Tanzania and worked for the then newly created United Nations. At Harvard, he became a Putnam Fellow in and He completed his Ph.
He published on moduli spaceswith a theory summed up in his book Geometric Invariant Theoryon the equations defining an abelian varietyand on algebraic surfaces. His books Abelian Varieties with C. Ramanujam and Curves on an Algebraic Surface combined the old and new theories.
This work on the equations defining abelian varieties appeared in —7. He published some further books of lectures on the theory.
Work on pathologies in algebraic geometry[ edit ] In a sequence of four papers published in the American Journal of Mathematics between andMumford explored pathological behavior in algebraic geometrythat is, phenomena that would not arise if the world of algebraic geometry were as well-behaved as one might expect from looking at the simplest examples.
These pathologies fall into two types: In the first Pathologies paper, Mumford finds an everywhere regular differential form on a smooth projective surface that is not closed, and shows that Hodge symmetry fails for classical Enriques surfaces in characteristic two.
Worse pathologies related to p-torsion in crystalline cohomology were explored by Luc Illusie Ann. Further such examples arise in Zariski surface theory. He also conjectures that the Kodaira vanishing theorem is false for surfaces in characteristic p.
In the third paper, he gives an example of a normal surface for which Kodaira vanishing fails. The first example of a smooth surface for which Kodaira vanishing fails was given by Michel Raynaud in Pathologies of moduli spaces[ edit ] In the second Pathologies paper, Mumford finds that the Hilbert scheme parametrizing space curves of degree 14 and genus 24 has a multiple component.
In the fourth Pathologies paper, he finds reduced and irreducible complete curves which are not specializations of non-singular curves.
These sorts of pathologies were considered to be fairly scarce when they first appeared. Classification of surfaces[ edit ] In three papers written between and the last two in collaboration with Enrico BombieriMumford extended the Enriques—Kodaira classification of smooth projective surfaces from the case of the complex ground field to the case of an algebraically closed ground field of characteristic p.
The final answer turns out to be essentially as the answer in the complex case though the methods employed are sometimes quite differentonce two important adjustments are made. The first is that one may get "non-classical" surfaces, which come about when p-torsion in the Picard scheme degenerates to a non-reduced group scheme.
The second is the possibility of obtaining quasi-elliptic surfaces in characteristics two and three. These are surfaces fibred over a curve where the general fibre is a curve of arithmetic genus one with a cusp. Once these adjustments are made, the surfaces are divided into four classes by their Kodaira dimensionas in the complex case.
The four classes are: These are the ruled surfaces. These are the K3 surfacesabelian surfaceshyperelliptic and quasi-hyperelliptic surfacesand Enriques surfaces. There are classical and non-classical examples in the last two Kodaira dimension zero cases. These are the elliptic and quasi-elliptic surfaces not contained in the last two groups.
These are the surfaces of general type. He was a MacArthur Fellow from to He won the Shaw Prize in In he was awarded the Wolf Prize ; on receiving the prize in Jerusalem from Shimon PeresMumford announced that he was donating half of the prize money to Birzeit University in the Palestinian territories and half to Gishaan Israeli organization that promotes the right to freedom of movement of Palestinians in the Gaza Strip.Authorship/referencing.
The terms 'activist', 'reflector', 'theorist', and 'pragmatist' are from a learning styles model developed by Honey and Mumford, and as such .
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The Honey & Mumford learner types are very popular and are widely used by teachers and students worldwide to determine how individual students learn best.
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