
 Sur les automorphismes bornés de corps munis d'opérateurs, with
Thomas Blossier and Charlotte Hardouin, to appear in Math. Research Letters,
Arxiv 1505.03669.
We give an alternative proof, valid in all characteristics, of a
result of Lascar characterising the bounded automorphisms of an
algebraically closed field. We generalise this method to various fields
equipped with operators.
 A Model Theoretic Study of RightAngled Buildings, with
Andreas Baudisch and Martin Ziegler, to appear in J. Eur. Math. Soc.
HAL01079813.
We study the model theory of countable rightangled buildings with infinite residues. For every Coxeter graph we obtain a complete theory with a natural axiomatisation, which is ωstable and equational. Furthermore, we provide sharp lower and upper bounds for its degree of ampleness, computed exclusively in terms of the associated Coxeter graph. This generalises and provides an alternative treatment of the free pseudospace.
 A la recherche du tore perdu, with T. Blossier et F. O. Wagner, J. Symbolic
Logic 81, (2016), 131,
HAL00758982.
We classify the groups definable in the coloured fields obtained by Hrushovski amalgamation.
A group definable in the bad green field is isogenous to the quotient of a subgroup of an
algebraic group by a Cartesian power of the group of green elements. A definable subgroup of
an algebraic group in the green or red field is an extension of a Cartesian power of the
subgroup of coloured elements by an algebraic group. In particular, a simple group in a
coloured field is algebraic.
 Géométries relatives, with T. Blossier et F. O. Wagner, J. Eur. Math. Soc. 17 (2015), 229258,
HAL00514393.
We start an analysis of geometric properties of a structure relative to a reduct. In particular,
we look at definability of groups and fields in this context. In the relatively onebased case,
every definable group is isogenous to a subgroup of a product of groups definable in the reducts.
In the relatively CMtrivial case, which contains certain Hrushovski amalgamations (the fusion of
two strongly minimal sets or the expansions of a field by a predicate), every definable group
allows a homomorphism with virtually central kernel into a product of groups definable in the reducts.
 De beaux groupes, with T. Blossier, Confl. Math. 6 (2014), 313,
HAL00837759.
In this short paper, we will provide a characterisation of interpretable groups in a
beautiful pair (K, E) of algebraically closed fields: every interpretable group is,
up to isogeny, the extension of the subgroup of Erational points of an algebraic group
by an interpretable group which is the quotient of an algebraic group by the Erational
points of an algebraic subgroup.
 Ample Hierarchy, with
Andreas Baudisch and Martin Ziegler, Fund. Math. 224 (2014), 97153, HAL00863214.
The ample hierarchy of geometries of stables theories is strict. We generalise
the construction of the free pseudospace to higher dimensions and show that the ndimensional free
pseudospace is ωstable nample yet not (n+1)ample. In particular, the free pseudospace is
not 3ample. A thorough study of forking is conducted and an explicit description of canonical
bases is exhibited.
 On variants of CMtriviality, with T. Blossier et F. O. Wagner, Fund. Math. 219 (2012), 253262,
HAL00702683.
We introduce a generalization of CMtriviality relative to a fixed invariant collection of partial
types, in analogy to the Canonical Base Property defined by Pillay, Ziegler and Chatzidakis which
generalizes onebasedness. We show that, under this condition, a stable field is internal to the
family, and a group of finite Lascar rank has a normal nilpotent subgroup such that the quotient is
almost internal to the family.
 Supersimplicity and quadratic extensions, with F. O. Wagner, Archive for Math. Logic 48 (2009), 5561,
HAL00863220.
Elliptic curves over a supersimple eld with exactly one extension of degree 2 have
sgeneric rational points.
 Sur les collapses de corps différentiels colorés en caractéristique nulle
décrits par Poizat à l'aide des amalgames à la Hrushovski, with T. Blossier,, J. Inst. Math. Jussieu 8 (2008),
445  464, HAL00261500.
We collapse Poizat's red fields in characteristic 0 to obtain a differentially closed field
of rank ω ⋅ 2 equipped with a definable additive subgroup of commensurable rank. We
obtain by using the logarithmic derivative a green multiplicative subgroup which cannot
be of finite rank.
 Die böse Farbe, with
Andreas Baudisch, Martin Hils and F. O. Wagner,
J. Inst. Math. Jussieu 8 (2007), 413443,
Modnet Preprint 12.
We construct a bad field in characteristic zero. That is, an algebraically closed field with a notion
of dimension analogous to Zariski dimension, equipped with an infinite proper multiplicative subgroup
of dimension one, such that the field itself has dimension 2. This answers a longstanding open question
by Zilber.
 Red fields, with
Andreas Baudisch and Martin Ziegler,
J. Symb. Logic 72 (2007), 207225,
Modnet Preprint 13.
We apply HrushovskiFraïssé's amalgamation procedure to
obtain a theory of fields of prime characteristic of Morley rank
2 equipped with a definable additive subgroup of rank 1.
 Hrushovski's Fusion, with
Andreas Baudisch and Martin Ziegler,
Algebra, Logic, Set Theory, Festschrift für Ulrich Felgner zum 65 Geburtstag., 2007,
Frieder Haug, Benedikt Löwe, Torsten Schatz (eds.), Studies in Logic, 4.
King's College Publications, London, U.K.,
Modnet Preprint 14.
We exhibit a simplified exposition of Hrushovski's fusion of two strongly minimal theories
over a trivial geometry.
 Fusion over a vectorspace, with
Andreas Baudisch and Martin Ziegler,
J. Math. Logic 6 (2006), 141162,
Modnet Preprint 39.
Given two countable strongly minimal theories with the DMP, whose common theory is the
theory of vector spaces over a fixed finite field, we show that the union of the two theories has a
strongly minimal completion.
 On fields and colors, with
Andreas Baudisch and Martin Ziegler,
Algebra and Logic 45 (2006), 92105,
arXiv:math/0605412.
We exhibit a simplified version of the construction of a field of
Morley rank p with a predicate of rank $p1$, extracting the main
ideas for the construction from previous papers and refining the
arguments. Moreover, an explicit axiomatization is given and ranks are computed.
 Galois cohomology of fields with a dimension, J. of Algebra 298 (2006), 3440,
(pdf).
We consider fields with an abstract notion of dimension as stated by Pillay and Poizat in their
paper of 1995. We prove that for every finite extension L of K and for every finite Galois extension
L_{1} of L , the Brauer group of L_{1} over L is finite, as well as the first cohomology
group of L_{1} over L with coefficients in some algebraic group G.
 Elliptic and Hyperelliptic Curves over Supersimple fields in characteristic 2, J. of pure and
applied Algebra 204 (2006), 368379,
(pdf).
In this paper, we extend a previous result of A. Pillay and the author regarding existence of
rational points over elliptic and hyperelliptic curves with generic moduli defined over supersimple
fields to the even characteristic case.
 Elliptic and Hyperelliptic Curves over Supersimple fields, with
Anand Pillay, J. of London Math. Soc.
69 (2004), 113,
(pdf).
It is proved that, if F is an infinite field with characteristic different from 2, whose theory
is supersimple, and C is an elliptic or hyperelliptic curve over F with generic modulus,
then C has a generic Frational point. The notion of genericity here is in the sense of the
supersimple field F.
