Daniel Dugger

Mapping spaces in Quasi-categories (2009)

Dugger, Daniel, Spivak, David I.

We apply the Dwyer-Kan theory of homotopy function complexes in model categories to the study of mapping spaces in quasi-categories. Using this, together with our work on rigidification from [DS1],...

Rigidification of quasi-categories (2009)

Dugger, Daniel, Spivak, David I.

We give a new construction for rigidifying a quasi-category into a simplicial category, and prove that it is weakly equivalent to the rigidification given by Lurie. Our construction comes from the...

Eigentheory of Cayley-Dickson algebras (2009)

Biss, Daniel K., Christensen, J. Daniel, Dugger, Daniel, Isaksen, Daniel C.

We show how eigentheory clarifies many algebraic properties of Cayley-Dickson algebras. These notes are intended as background material for those who are studying this eigentheory more closely.

ETALE HOMOTOPY AND SUMS-OF-SQUARES FORMULAS (2009)

Daniel Dugger, C. Isaksen

Abstract. This paper uses a relative of BP-cohomology to prove a theorem in characteristic p algebra. Specifically, we obtain some new necessary conditions for the existence of sums-of-squares...

EIGENTHEORY OF CAYLEY-DICKSON ALGEBRAS (2009)

Daniel K. Biss, J. Daniel Christensen, Daniel Dugger, C. Isaksen

Abstract. We show how eigentheory clarifies many algebraic properties of Cayley-Dickson algebras. These notes are intended as background material for those who are studying this eigentheory more...

Large annihilators in Cayley-Dickson algebras (2009)

Daniel K. Biss, J. Daniel Christensen, Daniel Dugger, C. Isaksen

Abstract. We establish many previously unknown properties of zero-divisors in Cayley-Dickson algebras. The basic approach is to use a certain splitting that simplifies computations surprisingly. 1.

Contents (2009)

Daniel Dugger, Brooke Shipley

Abstract. We show that if two rings have equivalent derived categories then they have the same algebraic K-theory. Similar results are given for G-theory, and for a large class of abelian categories.

The motivic Adams spectral sequence (2009)

Dugger, Daniel, Isaksen, Daniel C.

We present some data on the cohomology of the motivic Steenrod algebra over an algebraically closed field. We discuss several features of the associated Adams spectral sequence, including the basic...

ENRICHED MODEL CATEGORIES AND AN APPLICATION TO ADDITIVE ENDOMORPHISM SPECTRA (2008)

Daniel Dugger, Brooke Shipley

Abstract. We define the notion of an additive model category and prove that

4. Categories of k-invariants and Eilenberg-MacLane objects 9 (2008)

Daniel Dugger, Brooke Shipley

Abstract. We give a functorial construction of k-invariants for ring spectra, and use these to classify extensions in the Postnikov tower of a ring spectrum. Contents

Large annihilators in Cayley-Dickson algebras (2008)

Daniel K. Biss, Daniel Dugger, C. Isaksen

Abstract. Cayley-Dickson algebras are non-associative R-algebras that generalize the well-known algebras R, C, H, and O. We study zero-divisors in these algebras. In particular, we show that the...

ENRICHED MODEL CATEGORIES AND AN APPLICATION TO ADDITIVE ENDOMORPHISM SPECTRA (2008)

Daniel Dugger, Brooke Shipley

Abstract. We define the notion of an additive model category and prove that any

ENRICHED MODEL CATEGORIES AND AN APPLICATION TO ADDITIVE ENDOMORPHISM SPECTRA (2008)

Daniel Dugger, Brooke Shipley

Abstract. We define the notion of an additive model category and prove that any

A curious example of two model categories and some associated differential graded algebras (2007)

Dugger, Daniel, Shipley, Brooke

The paper gives a new proof that the model categories of stable modules for the rings Z/(p^2) and (Z/p)[\epsilon]/(\epsilon^2) are not Quillen equivalent. The proof uses homotopy endomorphism ring...

Large annihilators in Cayley-Dickson algebras II (2007)

Biss, Daniel K., Christensen, J. Daniel, Dugger, Daniel, Isaksen, Daniel C.

We establish many previously unknown properties of zero-divisors in Cayley-Dickson algebras. The basic approach is to use a certain splitting that simplifies computations surprisingly.

Etale homotopy and sums-of-squares formulas (2006)

Dugger, Daniel, Isaksen, Daniel C.

This paper uses a relative of BP-cohomology to prove a theorem in characteristic p algebra. Specifically, we obtain some new necessary conditions for the existence of sums-of-squares formulas over...

Classification spaces of maps in model categories (2006)

Dugger, Daniel

This paper corrects a small mistake in a paper of Dwyer-Kan, and uses this to identify homotopy function complexes in a model category with the nerves of certain categories of zig-zags.

Topological equivalences for differential graded algebras (2006)

Dugger, Daniel, Shipley, Brooke

We investigate the relationship between differential graded algebras (dgas) and topological ring spectra. Every dga C gives rise to an Eilenberg-Mac Lane ring spectrum denoted HC. If HC and HD are...

Postnikov extensions of ring spectra (2006)

Dugger, Daniel, Shipley, Brooke

We give a functorial construction of k-invariants for ring spectra, and use these to classify extensions in the Postnikov tower of a ring spectrum.

Enriched model categories and an application to additive endomorphism spectra (2006)

Dugger, Daniel, Shipley, Brooke

We define the notion of an additive model category, and we prove that any additive, stable, combinatorial model category has a natural enrichment over symmetric spectra based on simplicial abelian...

Spectral enrichments of model categories (2006)

Dugger, Daniel

We prove that every stable, presentable model category can be enriched in a natural way over symmetric spectra. As a consequence of the general theory, every object in such a model category has an...

Topological equivalences for differential graded algebras (2006)

Daniel Dugger, Brooke Shipley

Abstract. We investigate the relationship between differential graded algebras (dgas) and topological ring spectra. Every dga C gives rise to an Eilenberg-Mac Lane ring spectrum denoted HC. If HC and...

Large annihilators in Cayley-Dickson algebras (2005)

Biss, Daniel K., Dugger, Daniel, Isaksen, Daniel C.

Cayley-Dickson algebras are an infinite sequence of non-associative algebras starting with the reals, complexes, quaternions, and octonions. We study the zero-divisors in the higher Cayley-Dickson...

Spectral enrichments of model categories (2005)

Dugger, Daniel

We prove that every stable, combinatorial model category has a natural enrichment by symmetric spectra (or more precisely, a natural equivalence class of enrichments). This in some sense generalizes...

C.: Motivic cell structures (2005)

Daniel Dugger, Daniel C. Isaksen

Abstract An object in motivic homotopy theory is called cellular if it can be built out of motivic spheres using homotopy colimit constructions. We explore some examples and consequences of...

Documenta Math. 357 Algebraic K-Theory and Sums-of-Squares Formulas (2005)

Daniel Dugger, Daniel C. Isaksen, Communicated Stefan Schwede

Abstract. We prove a result about the existence of certain ‘sums-ofsquares’ formulas over a field F. A classical theorem uses topological K-theory to show that if such a formula exists over R,...

K-theory and derived equivalences (2004)

Dugger, Daniel, Shipley, Brooke

We show that if two rings have equivalent derived categories, then they have the same algebraic K-theory. Similar results are given for G-theory and for a large class of abelian categories.

Notes on the Milnor conjectures (2004)

Dugger, Daniel

These are some notes on the two Milnor conjectures and their proofs (due to Voevodsky, Orlov-Vishik-Voevodsky, and Morel).

Algebraic K-theory and sums-of-squares formulas (2004)

Dugger, Daniel, Isaksen, Daniel C.

We prove a result about the non-existence of certain sums-of-squares formulas over a field. This generalizes an old theorem which used topological K-theory to obtain obstruction conditions when the...

DOI: 10.1007/s00209-003-0607-y Topological hypercovers and A 1-realizations (2004)

Daniel Dugger, Daniel C. Isaksen

Abstract. We show that if U ∗ is a hypercover of a topological space X then the natural map hocolim U∗→X is a weak equivalence. This fact is used to construct topological realization functors...

Motivic cell structures (2003)

Dugger, Daniel, Isaksen, Daniel C.

An object in motivic homotopy theory is called cellular if it can be built out of motivic spheres using homotopy colimit constructions. We explore some examples and consequences of cellularity. We...

The Hopf condition for bilinear forms over arbitrary fields (2003)

Dugger, Daniel, Isaksen, Daniel C.

We settle an old question about the existence of certain "sums-of-squares" formulas over a field F (which are the simplest examples of composition formulas for quadratic forms). A classical theorem...

Multiplicative structures on homotopy spectral sequences II (2003)

Dugger, Daniel

The paper summarizes the construction of pairings on some standard spectral sequences in algebraic topology.

Multiplicative structures on homotopy spectral sequences I (2003)

Dugger, Daniel

This mostly expository paper records some basic facts about towers of homotopy fiber sequences. We give a proof that a pairing of towers induces a pairing of associated spectral sequences, for towers...

An Atiyah-Hirzebruch spectral sequence for KR-theory (2003)

Dugger, Daniel

We construct a spectral sequence for computing KR-theory, analogous to the spectral sequence relating motivic cohomology to algebraic K-theory.

K-theory and derived equivalences (2002)

Dugger, Daniel, Shipley, Brooke

We show that if two rings have equivalent derived categories then they have the same algebraic K-theory. Similar results are given for G-theory, and for a large class of abelian categories.

Weak equivalences of simplicial presheaves (2002)

Dugger, Daniel, Isaksen, Daniel C.

The usual way of defining weak equivalences for simplicial presheaves is to require an isomorphism on all sheaves of homotopy groups. We unravel some of the machinery here, and give a more concrete...

Hypercovers and simplicial presheaves (2002)

Dugger, Daniel, Hollander, Sharon, Isaksen, Daniel C.

We prove that Jardine's model category of simplicial presheaves can be obtained by localizing the `discrete' version at the collection of all hypercovers. One consequence is that the fibrant objects...

DOI: 10.1017/S0305004103007175 Printed in the United Kingdom Hypercovers and simplicial presheaves (2002)

Daniel Dugger, Sharon Hollander, Daniel C. Isaksen

We use hypercovers to study the homotopy theory of simplicial presheaves. The main result says that model structures for simplicial presheaves involving local weak equivalences can be constructed by...

K-Theory And Derived Equivalences (2002)

Daniel Dugger, Brooke Shipley

We show that if two rings have equivalent derived categories then they have the same algebraic K-theory. Similar results are given for G-theory, and for a large class of abelian categories.

Hypercovers in topology (2001)

Dugger, Daniel, Isaksen, Daniel C.

We show that if U is a hypercover of a topological space X then the natural map from hocolim U to X is a weak equivalence. This fact is used to construct topological realization functors for the...

Combinatorial model categories have presentations (2000)

Dugger, Daniel

We show that every combinatorial model category can be obtained, up to Quillen equivalence, by localizing a model category of diagrams of simplicial sets. This says that any combinatorial model...

Universal homotopy theories (2000)

Dugger, Daniel

Given a small category C, we show that there is a universal way of expanding C into a model category, essentially by formally adjoining homotopy colimits. The technique of localization becomes a...