Errata and Addenda for Algebraic Geometry I

Here we post a list of errata and addenda. The name tags refer to the people who found the mistake. We are very grateful to all of them. Further remarks and hints - trivial or not - are very welcome.

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Explanation: Major error Minor error Typo/Trivial Remark Unclassified

p. 0 - VII,
Contents of Chapter 16
The page numbers given for the last 3 sections of Chapter 16 should be increased by one. p.528 should be p.529, p.532 should be p.533, p.539 should be p.540. (F. Ebert)
p. 2,
Line -8
Replace 1994 by 1995. (J. Hilgert)
p. 5,
Line 12
then $X$ inherits many properties of $X'$ (rather than: of $X$) (P. Barik)
p. 7,
Figure 1
Replace $T_2^2-T_1^2(T_1+1)$ by $T_2^2-T_1^2(T_1+1)=0$. (A. B. Nguyen)
p. 10,
Line -17
Omit ``We will not use this characterization for the proof of the Nullstellensatz.''. A simple form of it is used in the beginning of the proof of Lemma~1.9. (J. Hilgert)
p. 10,
Line 17
The definition of finite ring homomorphism is messed up. Replace it by: A homomorphism $R \rightarrow R'$ of rings is finite, if it is integral and $R'$ is generated as an $R$-algebra by finitely many elements. (K. Mohri, C. Frank)
p. 10,
Line -3
Replace $\beta_{n-1}+\beta_{n-2}a+\cdots +a^{n-1}$ by $-(\beta_{n-1}+\beta_{n-2}a+\cdots +\beta_0 a^{n-1})$. (P. Zsifkovits)
p. 10,
Theorem 1.8
Add the assumption that $A\ne 0$. (D. Gerigk)
p. 13,
Line 15
Replace nonconnected by non-connected. (P. Zsifkovits)
p. 13,
Line -7
After ``hence'', add ``if $Z \cap U \ne \emptyset''. (U. Görtz)
p. 14,
Line 10
Replace ``$\emptyset \ne J \subset I$'' by ``$\emptyset \ne J \subsetneq I$''. (J. Buck)
p. 14,
Line 14
Replace ``than'' by ``then'' and omit ``be''. (P. Zsifkovits)
p. 15,
Line -15
Replace "there existed" with "there would exist". (F. Gispert Sánchez)
p. 15,
Line 14
Replace ``Every open subset'' by ``Every subspace''. (T. Wedhorn)
p. 15,
Line 15
Replace ``Every closed subset'' by ``Every subspace''. (T. Wedhorn)
p. 16,
Line -13
Omit superfluous (. (P. Zsifkovits)
p. 16,
Line -16
Replace $T_2-T_1^2$ by $T_1-T_2^2$. (P. Zsifkovits)
p. 19,
Line 9
In the diagram exchange $m$ and $n$. (J. Buck)
p. 19,
Line 14
Insert ``$A$'' after ``$k$-algebra''. (J. Buck)
p. 19,
Line -15
Replace ``Proposition 1.20'' by ``Proposition 1.32''. (P. Zsifkovits)
p. 19,
Line 11
In the definition of $f$ add the missing bracket at the end. (T. Przezdziecki)
p. 20,
Line -15
Replace ``set morphisms'' by ``set of morphisms''. (P. Zsifkovits)
p. 23,
Line 6
Replace ``manifolds'' by ``manifold''. (J. Buck)
p. 23,
Line 15 (Def. 1.46.2)
Replace ``finite covering'' by ``finite open covering''. (F. Gispert Sánchez)
p. 24,
Proof of Lemma 1.50
The reduction step in the first paragraph is superfluous because the rest of the proof shows that $D(f)$ and $Y$ are isomorphic spaces of functions. (Menachem Dov Mostowicz)
p. 26,
Line -13
Replace $k$ by $R$. (D. Gerigk)
p. 28,
Line 7
Replace "space with function" with "space with functions". (F. Ebert)
p. 28,
Displayed equation in prop. 1.59
Replace ``exist'' by ``$\exists$''. (P. Zsifkovits)
p. 29,
Line 2
Replace "space with function" with "space with functions". (F. Gispert Sánchez)
p. 29,
Line 7
Add $g \ne 0$ in the description of the function field of $K({\mathbb P}^n(k))$. (T. Wedhorn)
p. 29,
Line 8
Replace ``is then given by'' by ``is given abstractly by''. Furthermore, the map $K(U_i) \rightarrow K(U_j)$ maps $\frac{X_\ell}{X_i} \mapsto \frac{X_\ell}{X_j}\frac{X_j}{X_i} = \frac{X_\ell}{X_i}$. (I.e., as subfields of $K(X_0, \dots, X_n)$, the $K(U_i)$ all coincide, and coincide with $K(\mathbb P^n(k))$, and the isomorphism induced by our identifications is the identity map.) (M. Kaneda)
p. 33,
Lines 4 and 6
Replace $\mathbb P^n$ with $\mathbb P^m$ and $\mathbb A^n$ with $\mathbb A^m$. (Safak Ozden)
p. 35,
Figure 1.2
Replace $X^2+Y^2-1$ by $X^2+Y^2=1$ and $XY-1$ by $XY=1$. (A. B. Nguyen)
p. 35,
Line 4
$r \gt 2$ (rather than: $r \gt 1$) (P. Barik)
p. 36,
Line -1
Replace ``connected'' by ``not connected with respect to the analytic topology''. (T. Wedhorn)
p. 38,
Exercise 1.21 (3)
Remove "in" in "The set of closed affine cones in $C\subseteq \mathbb A^{n+1}(k)$". (Menachem D. Mostowicz)
p. 44,
Proposition 2.10
Replace ``Let $A$ be a ring.'' by ``Let $\varphi\colon A\rightarrow B$ be a ring homomorphism.''. (U. Görtz)
p. 48,
Line -3 (def. 2.18.Sh2)
Replace "by (a)" with "by (Sh1)". (F. Gispert Sánchez)
p. 48,
Line 9
Add the ``category of abelian groups'' as the first example. (A. Kaučikas)
p. 50,
Section 2.6 Line 3
Maybe replace ``containment'' by ``reverse containment'' or state explicitly in which direction the order goes. ()
p. 50,
Prop. 2.20
The basis B has to be closed under finite intersections for the (Sh) condition to be well-defined. (In Lemma 1.31 the notion of basis of topology is "defined", in passing, by requiring also that it is stable under finite intersections; but this appears to be non-standard terminology, so both places should be fixed.) (Florian Ebert)
p. 51,
Line 12
Replace ``if and only of'' by ``if and only if''. (J. Watterlond)
p. 53,
Line -2
Since $f^{-1}$ includes sheafification by definition, the restriction $\mathscr G_{|X}$ to an open subspace in this sense coincides with Example 2.19 (1) only if $\mathscr G$ is a sheaf. (E. Viehmann)
p. 54,
Line 2
Replace ``$X$'' by ``$Y$''. (K. Mohri)
p. 54,
Line 3
Replace ``$f(V)$'' by ``$f(U)$''. (K. Mohri)
p. 54,
Line -9
Replace ``sheaves'' by ``presheaves''. (J. Watterlond)
p. 54,
Proof of Prop. 2.27
Introducing the element $t$ could be avoided. (E. Viehmann)
p. 55,
Line 11
Replace ``statements'' by ``statement''. (D. Gerigk)
p. 55,
Line -13
Insert "$U$" after "open subset". (F. Ebert)
p. 58,
Line -2
The third sum should be over the index set $I$ instead of $J$. (Sebastian Schlegel Mejia)
p. 61,
Lines -3, -2
Replace ``$\mathfrak a$'' by ``$\mathfrak a_1$'' and ``$\mathfrak b$'' by ``$\mathfrak a_2$''. (P. Zsifkovits)
p. 62,
Exercise 2.3 line 2
Change "every open subset" to "every non empty open subset" (Vishal Gupta)
p. 63,
Line 8 (ex. 2.9 (d))
Replace "$u \in A$" with "$u \in R$". (F. Gispert Sánchez)
p. 64,
Ex.~2.14 (c)
The condition that $Z$ is locally connected is not sufficient. It should be replaced by the condition that every point in the closure of $Z$ has a fundamental system of open neighborhoods which intersect $Z$ in a connected set. (J. Calabrese)
p. 64,
Line 19 (Exercise 2.16)
Replace "show an analogous results" by "show that an analogous result holds". ()
p. 67,
Prop.+Def. 3.2 (2)
Note that the affine open subschemes are not closed under finite intersections. This is inconsistent with the notion of a basis of a topology "defined" in Lemma 1.31. (F. Ebert)
p. 67,
Line -6
Replace ``constitute homomorphism'' by ``constitute a homomorphism''. (D. Gerigk)
p. 68,
Use consistent terminology: ``principal open'' or ``principally open'' subset. (E. Viehmann)
p. 71,
Example 3.12
Replace ``$\prod_{i=1}^n A_i$'' by ``$\mathop{\rm Spec}\prod_{i=1}^n A_i$''. (P. Zsifkovits)
p. 71,
Line 18
$U \subseteq \psi_i(U_i) \cap \psi_j(U_j)$ (rather than: $U \subseteq U_i \cap U_j$) (P. Barik)
p. 72,
Line -9
Exchange the indices $\frac{X_i}{X_j}$ and $\frac{X_j}{X_i}$. (F. Grelak)
p. 73,
15
Replace ``subset'' by ``a subset''. (E. Viehmann)
p. 76,
Line 20
Replace ``ideals'' by ``ideal''. (D. Gerigk)
p. 77,
Line 12
Replace ``scheme'' by ``non-empty scheme''. (M. Jarden)
p. 78,
Prop. 3.29 (3)
Add the assumption that all $U_i$ are non-empty. (D. Gerigk)
p. 78,
End of proof of Prop. 3.29(3)
It might be worthwile to spell out the argument of Example 2.37 more explicitly. (E. Viehmann)
p. 79,
Line 12
Replace "if follows" with "it follows". (F. Gispert Sánchez)
p. 79,
Line 14
Replace ``locally finite type'' by ``locally of finite type''. (J. Watterlond)
p. 79,
Proposition 3.33
It might be worthwile to aim for a consistent notation for algebraically closed vs. not necessarily algebraically closed fields (e.g., $k$ versus $K$). (V. Gupta)
p. 80,
Corollary 3.36
Make it more explicit that $k=\kappa(x)$ means that the natural homomorphism $k\rightarrow\kappa(x)$ is an isomorphism (rather than just the existence of any isomorphism between these two fields). (Similarly on page 119, Equation (5.2.1).) (V Gupta)
p. 81,
Line 11, line 21
"Definition 1.15" should be replaced with "Definition 1.46". In line 21, replace "is the sense" by "in the sense". (Alexander Isaev)
p. 82,
Line 13
Replace ``points'' by ``type''. (D. Gerigk)
p. 85,
Proof of Thm. 3.42, Condition (2)
Omit ``and $x \not\in U_i$ for all $i$'' (this is neither (a priori) possible in general, e.g. if $X$ is irreducible and $x$ its generic point, nor necessary in the sequel of the proof). (B. Heintz)
p. 85,
Line 14
Replace "$\varphi(g)|U$" with "$\varphi(g)_{|U}$". (F. Gispert Sánchez)
p. 85,
Line -17
Replace ``biggest'' by ``largest''. (P. Johnson)
p. 88,
3rd line of the proof of Prop. 3.52
Replace "on" by "in" in the sentence "[...] $Z$ is closed on $U$". ()
p. 90,
Ex. 3.19
The set $(R^{n+1}\setminus\{0\})/R^\times$ must be replaced by the set $M/R^\times$, where $M\subset R^{n+1}$ denotes the subset of all tuples which have at least one entry in $R^\times$. (B. Heintz)
p. 90,
Ex. 3.14
Add the assumption that the maximal ideal of $A$ is the union of all prime ideals properly contained in it. See Knaf's answer to this question on MathOverflow. (B. Heintz)
p. 90,
Exercise 3.13
$X$ should be nonempty. ()
p. 92,
Line -5
Replace ``shows'' by ``show''. (P. Zsifkovits)
p. 94,
Line -3 (ex. 4.5)
Replace "Equivalent" with "Equivalently". (F. Gispert Sánchez)
p. 94,
Example 4.4
Conflict of notation: $T$. (E. Viehmann)
p. 94,
Example 4.5
Insert: ``Let $\pi\colon R[T_1,\dots, T_n]\rightarrow R$ be the projection mapping each $T_i$ to $0$.'' after the definition of the $a_i$. (P. Zsifkovits/F. Gispert Sánchez)
p. 95,
Line 7
Replace "objects" with "object". (F. Gispert Sánchez)
p. 97,
Definition 4.10
Add the condition that $f \circ p = g \circ q$. (C. Frei)
p. 100,
-9
"are morphisms" should be replaced by "be morphisms". (Kuo Tzu-Ang)
p. 101,
Prop. 4.20, Condition (I)
Replace ``affine neighborhood $U'$ of $x'$'' by ``affine neighborhood $U'$ of $f(x')$''. (B. Heintz)
p. 101,
Prop. 4.20, condition (I)
The proof of the proposition when condition (I) holds uses the fact that all the assertions can be checked locally. However, to pass to the affine situation, one also needs to know that for every open neighborhood $U''$ of $f(x')$ contained in $U'$, $f^{-1}(U'')$ is also quasi-compact. This is true (Prop. 10.1) but had not been stated at this point. (F. Gispert Sánchez)
p. 101,
Line -7
In the statement of Prop. 4.20, maybe it should be made clearer that the assumptions (I) and (II) should refer to each factor of $f$, namely if $f=f_r\cdots f_1$, then each $f_i$ should satisfy one of the assumptions (I) and (II) (not $f$ itself). (Peng Du)
p. 102,
Proof of Prop. 4.20, Case (II)
To see that $(p^{-1}(f(X')), \mathscr O_{Z|p^{-1}(f(X'))})$ is a fiber product in the category of schemes, one needs to know that the fiber product of schemes taken in the category of locally ringed spaces exists and is a scheme. This stronger version of Thm. 4.18 should have been stated and proved before. It is proved similarly as Thm. 4.18; for the affine case use Proposition 3.4 in the form given (but not proved) in the book. (O. Körner)
p. 102,
Line -10
Replace "homomorphisms" by "homomorphism" (... "is injective"). (F. Gispert Sánchez)
p. 104,
Line -3
Replace ``be'' by ``by''. (U. Görtz)
p. 104,
Line 13
Add "Let" before "$X$ and $Y$ be". (F. Gispert Sánchez)
p. 105,
Line -6
Insert ``be'' before ``the first projection''. (P. Zsifkovits)
p. 106,
Line -2
Add missing parenthesis. (P. Zsifkovits)
p. 106,
Line 4
Replace ``(applied to $X, S, X' = \mathop{\rm Spec} \kappa(s), Y=S$)'' by ``(applied to $S, X = S, X' = \mathop{\rm Spec} \kappa(s), Y=X$)''. (P. Zsifkovits)
p. 107,
Line -10 (def. 4.31)
Replace "morphism of $f\colon X\rightarrow S$ of $S$-schemes" by "morphism $f\colon X\rightarrow S$ of schemes". (F. Gispert Sánchez)
p. 107,
Line 20 (proof of prop. 4.30)
Replace "$(f \times_S id_Y)\circ (id_X \times_S g)$" with "$(f \times_S id_Y)\circ (id_{X'} \times_S g)$". (F. Gispert Sánchez)
p. 108,
Line -6 (prop. 4.34)
Replace "immersion" with "immersions". (F. Gispert Sánchez)
p. 108,
Proof of Prop. 4.32
Replace second sentence by: ``Proposition 4.20 shows that the properties immersion, open immersion and closed immersion are stable under base change (see the discussion at the beginning of (4.11)).'' (P. Zsifkovits)
p. 108,
Line -14
Replace "locally" by "local". (F. Gispert Sánchez)
p. 111,
Line -10
Replace ``$g(a)$'' by ``$g(a)=0$''. (P. Zsifkovits)
p. 118,
Line 11
Replace "arbitrary morphism" with "arbitrary morphisms". (F. Gispert Sánchez)
p. 120,
l. 9
Replace "Corollary 3.33" by "Proposition 3.33". (M. Pereira)
p. 121,
Line 9
Replace $\mathfrak p_0$ by $\mathfrak p_0 A[T]$, and correspondingly for $\mathfrak p_r$. (P. Zsifkovits)
p. 126,
Proof of Prop. 5.20
Replace the last sentence by: Corollary 5.17 shows that the structure morphism $X\rightarrow \mathop{\rm Spec} k$ corresponds to a finite homomorphism $k\rightarrow A$. (P. Hartwig)
p. 126,
Theorem 5.22
Replace "of finite type" with "locally of finite type". (This slightly more general statement is used in the proof of Proposition 5.26, for example.) Note that the proof does not use the finiteness of the affine open cover. (F. Gispert Sánchez)
p. 127,
Line -3
Replace "$\sup_{Z\in I} (Z\cap U)$" with "$\sup_{Z\in I} \dim(Z\cap U)$" (F. Gispert Sánchez)
p. 133,
Cor. 5.45
Add the hypothesis that $Y$ be non-empty. ()
p. 134,
Line 18
Replace ``$X=\mathop{\rm Spec} B$'' by ``$Y=\mathop{\rm Spec} B$''. (K. Kidwell)
p. 134,
Proof of Cor. 5.47
Note that the first statement in the proof holds by Cor. 5.23. (K. Kidwell)
p. 142,
Line -14 (ex. 5.11)
In the definition of the special orthogonal group scheme SO, the condition that the determinant must be +1 is missing. (F. Gispert Sánchez)
p. 142,
Exercise 5.7
Before the first ``Show'', add ``Let $X=\mathop{\rm Spec} A[T]$.'' (A. Steinbach)
p. 143,
Line -6 (ex. 5.20)
Replace "$x\in X_{\Omega}$" with "$x' \in X_{\Omega}$" (F. Gispert Sánchez)
p. 144,
Line 10 (ex. 5.21)
Replace "intgral" with "integral". (F. Gispert Sánchez)
p. 146,
l. $-8$
Replace ``heuristics'' by ``heuristic''. (P. Johnson)
p. 148,
Line -10
$D(g_1 \cdots g_s)$ should instead read $D(g_1 \cdots g_r)$. (Nathan Pflueger)
p. 149,
Lines -8, -7
Remove "is in $T_x X$". (F. Gispert Sánchez)
p. 153,
Def. 6.14 (2)
Replace ``in all points'' by ``at all points''. (P. Johnson)
p. 157,
Statement of Lemma 6.22
Replace $\partial\varphi(Y_j)$ by $\partial\varphi(Y_i)$ and $\partial X_i$ by $\partial X_j$. (B. Smithling)
p. 157,
Proof of Prop. 6.23
Instead of ``renumbering the $f_i$'', we need to renumber the $T_i$ such that the $(r \times r)$ minor given by the first $r$ columns of $J$ does not vanish at $x$. (B. Smithling)
p. 159,
Proof of Lemma 6.27
In the second line of the proof, replace ``columns'' by ``rows''. (B. Smithling)
p. 159,
Proof of Lemma 6.26
Replace ``By Example 6.5'' by ``By the argument in Example 6.5'' and/or add explanation why we obtain the desired linear independence over $\kappa(y)$ even though $y$ might not be a $k$-valued point. (P. Johnson)
p. 159,
Line 12
Replace $T_{\mathbb A^n_k, y}$ by $T_{\mathbb A^n_k, y}^*$. (F. Gispert Sánchez)
p. 160,
Line 9
Replace "point of $x$" with "point of $X$". (F. Gispert Sánchez)
p. 161,
Lines 4, 5 (cor. 6.31)
The two ranks in the statement of the corollary should be of the Jacobian matrix evaluated at $x$: replace "$\partial g_i / \partial T_j$" by "$\frac{\partial g_i}{\partial T_j}(x)$" (twice). (F. Gispert Sánchez)
p. 162,
Remark 6.37
Replace the final sentence of the remark by: If a point in an arbitrary scheme lies on more than one irreducible component, then its local ring will have more than one minimal prime ideal and hence cannot be an integral domain. In particular, such a point is not normal. (U. Hartl/B. Smithling)
p. 163,
Line 17
Replace ``$\dim {\mathscr O}_{X,x} = 2$'' by ``$\dim {\mathscr O}_{X,x} \geq 2$''. (T. Wedhorn)
p. 165,
Line 17 (ex. 6.4)
Replace "$df_{(e,e)}$" with "$dm_{(e,e)}$". (F. Gispert Sánchez)
p. 171,
Line 4
Replace "homomorphism" with "homomorphisms". (F. Gispert Sánchez)
p. 175,
Line -3
Maybe the tensor symbols $\otimes$ should be accompanied by O_X(U) as a subscript. (Victor Zhang)
p. 177,
Line -11
Replace "$\mathscr{F}_{|U} \otimes_{\mathscr{O}_U} \mathscr{H}_{|U}$" by "$\mathscr{G}_{|U} \otimes_{\mathscr{O}_U} \mathscr{H}_{|U}$". (F. Gispert Sánchez)
p. 178,
Line 19
The morphism "$\iota$" has not been defined; it should be (7.5.7). (F. Gispert Sánchez)
p. 181,
Line -7
Replace "and" by "an". (F. Gispert Sánchez)
p. 185,
Corollary 7.19. (4)
Define $\mathscr{F}$ and $\mathscr{G}$ to be quasi-coherent $\mathscr{O}_X$-modules. (F. Ebert)
p. 186,
Line 18
Replace "(7.4)" by "(7.5)". (Invertible $\mathscr{O}_X$-modules are explained at the end of section (7.5).) (F. Gispert Sánchez)
p. 189,
Line -13
Replace "$\mathscr{L}_{|U_x}$" by "$\mathscr{L}_{D|U_x}$" (F. Gispert Sánchez)
p. 190,
Line -15
Add "be" before "extended". (F. Gispert Sánchez)
p. 191,
Commutative diagram
In the right-most column, replace $n$ by $m$ in both rows. (P. Carlucci)
p. 191,
Line -2
Replace "$X''$" by "$U''$". (F. Gispert Sánchez)
p. 191,
Line -1
Replace "generated" by "generate". (F. Gispert Sánchez)
p. 195,
Proof of Lemma 7.42
`The corresponding homomorphism $A'^n \to M'$` should be `The corresponding homomorphism $A'^r → M'$`; similarly, `an isomorphism $A^r_s \to M^r_s$' should be `an isomorphism $A^r_s \to M_s$'. (Kannappan Sampath)
p. 202,
Exercise 7.20
Replace ${\mathscr F}$ by ${\mathscr G}$. (J. Calabrese)
p. 204,
Line 4 (ex. 7.32)
Replace "send" with "sent". (F. Gispert Sánchez)
p. 206,
Prop. 8.4
It might be helpful to add a Remark after the Proposition pointing out that as a formal consequence one gets the following: Let $S$ be a scheme, let $X$ be an $S$-scheme, and let $v$ be a homomorphism of quasi-coherent $\mathscr{O}_X$-modules. Then the functor $F'$ on $S$-schemes with $F'(T) = \{ f\in \mathop{\rm Hom}_S(T,X);\ f^*(v)\ \text{surjective} \}$ is representable by an open subscheme of $X$. (Apply the original proposition to $X$, $v$ to obtain an open subscheme $U$ of $X$, and observe that the $S$-scheme $U$ represents the functor $F'$. This is how the Proposition is often used later, e.g., in the proof of Lemma 8.13. (Likewise for part (2) of the proposition and other similar statements, like Theorem 11.17.) (F. Gispert Sánchez)
p. 211,
Line 9
Replace ``bijective'' by ``an isomorphism''. (Ulrich Görtz)
p. 211,
Line -7
Add "of" between "homomorphism" and "$\mathscr{O}_S$-modules". (F. Gispert Sánchez)
p. 212,
Line -16
Insert ``and is'' before ``also''. (D. Gerigk)
p. 212,
Line -5
Replace "subvector space of $K^n$" by "subvector space $U$ of $K^n$". (F. Gispert Sánchez)
p. 216,
Line -7
Replace "disjoint sum" with "disjoint union". (F. Gispert Sánchez)
p. 216,
Line 4
Replace "of $\mathscr{O}_S$-module" by "of $\mathscr{O}_S$-modules". (F. Gispert Sánchez)
p. 219,
Def. 8.25
Insert $S$ before the first ``such that''. (D. Gerigk)
p. 220,
Line 4
Replace "$(v,u)$" by "$(v,s)$". (F. Gispert Sánchez)
p. 221,
Line -13
Insert "points" between "$R$-valued" and "of". (F. Gispert Sánchez)
p. 224,
Exercise 8.11
Repace ${\mathscr G}$ by $f^*{\mathscr G}$, and the map $f^*{\mathscr G} \to f^*{\mathscr E}$ will not be injective in general. (L. Galinat)
p. 226,
Line 20
Replace ``separable'' by ``separated''. (T. Wedhorn)
p. 226,
Lines 10/12
Replace ``$\{(x,f(x)) ; x \in X\}$ is closed in $X\times Y$'' by ``$\{(y,f(y)); y \in Y\}$ is closed in $Y\times X$'' in (ii), and replace ``$\{x \in X; f(x) = g(x)\}$ is closed in $X$'' by ``$\{y \in Y; f(y) = g(y)\}$ is closed in $Y$'' in (iii). (O. Das)
p. 227,
Line 19
Replace "an $S$-objects" by "an $S$-object". (F. Gispert Sánchez)
p. 228,
Statement of Prop. 9.3 (3)
Replace $f$ by $u$ everywhere (i.e., in 3 places). (K. Kidwell)
p. 229,
Line 13
Replace "$p\colon X\times_S Y$" by "$p\colon X\times_S Y \to X$". (F. Gispert Sánchez)
p. 230,
Lines 14, 15
Replace $X\rightarrow X_{\rm red}$ by $X_{\rm red}\rightarrow X$, and likewise for $Y$, and replace $f_{\rm red}\circ i_Y$ by $i_Y\circ f_{\rm red}$. (P. Barik/U. Hartl)
p. 232,
Lines 6-9
Replace "Grass$_{n,n-e}$" with "Grass$_{n-e,n}$" (4 times) to keep the same notation as in chapter 8. (F. Gispert Sánchez)
p. 233,
Prop. 9.19 (iii)
$f$ and $g$ should be $S$-morphisms. (K. Kidwell)
p. 233,
Def. 9.21
Replace ``$\mathfrak p_x$'' by ``$\mathfrak m_x$''. (A. Isaev)
p. 234,
Line 28 (Remark 9.25)
Replace ``can checked'' by ``can be checked''. (L. Galinat)
p. 234,
Line 30 (Remark 9.25)
Replace $U\subseteq S$ by $U\subseteq X$. (P. Barik)
p. 235,
Def. 9.26
Our definition of rational map is different from that in other places in the literature. Notably, in EGA I (new ed.) 8.1, it is not required that the open subset $U$ be schematically dense. Cf. however the notion of pseudo-morphism introduced in EGA IV, 20.2. (P. Hartwig)
p. 235,
Line 9
The claimed injectivity does not hold in general. It does hold if $Y$ is separated over $S$ (by Prop. 9.19). (K. Kidwell)
p. 236,
Line 5
Replace "$(\lambda,\mu)$" with "$(\lambda : \mu)$". (F. Gispert Sánchez)
p. 236,
Line -3
Replace "$K$" with "$K(X)$". (F. Gispert Sánchez)
p. 237,
Line 24 (Remark 9.34)
Replace $f\colon - - \rightarrow Y$ by $f\colon X - - \rightarrow Y$. (P. Barik)
p. 237,
Line -16
Replace "tape" with "type". (F. Gispert Sánchez)
p. 238,
Line 17 (Exercise 9.2)
Replace ``$X \times_S Y \to X \times_S Y$'' by ``$X \times_S Y \to X \times_T Y$'' (L. Galinat)
p. 242,
Rmk. 10.2 (4)
At the end, replace ``if $Y$ not separated'' by ``if $Y$ is not separated''. (U. Hartl)
p. 248,
Line -14
Replace "on" with "an". (F. Gispert Sánchez)
p. 248,
Line 9
Replace ``ad'' by ``and''. (U. Hartl)
p. 249,
Line 1
Replace "$\mathscr{O}_{Y,f(y)}$" with "$\mathscr{O}_{Y,f(x)}$" (F. Gispert Sánchez)
p. 251,
Lines 29, 31 (Proof of Prop. 10.30)
Replace $i\colon Z\rightarrow X$ by $i\colon Z\rightarrow Y$ and $i^\flat$ by $i^\flat \colon \mathscr O_Y \rightarrow i^* \mathscr O_Z$. (P. Barik)
p. 253,
Remark 10.40 (3)
Add the assumption that $X$ has a basis of retro-compact open subsets. (A. Gross)
p. 255,
Line 4
Replace $Z$ by $C$. (P. Barik)
p. 256,
Line 18 (Cor. 10.49)
In the conclusion of the corollary, add that $\mathscr{F}$ is also quasi-coherent. (F. Gispert Sánchez)
p. 257,
Line 7
Replace "an" with "a". (F. Gispert Sánchez)
p. 264,
Line 2
Replace "1., 3., 5." with "1.-3., 5.". (F. Gispert Sánchez)
p. 265,
l. $-2$
Replace ``$R$-scheme'' by ``of $R$-schemes''. (U. Hartl)
p. 265,
Line -15 (cor. 10.67)
Add "of" between "morphism" and "$S$-schemes". (F. Gispert Sánchez)
p. 267,
Line -10 (prop. 10.75)
Replace "$f$" with "$f_0$". (F. Gispert Sánchez)
p. 268,
Line 22
Replace "morphism" with "morphisms". (F. Gispert Sánchez)
p. 268,
Theorem 10.76
It is not true in general that $B$ is the inductive limit of its smooth $A$-sub-algebras. All one can say in general is that $B$ is isomorphic to a filtered inductive limit of smooth $A$-algebras. See the discussion in Spivakovsky's paper [Sp] (Problem 1.3; Section 10). (M. Hoyois, S. Kelly)
p. 268,
l $-2$
Remove one ``that'' and replace ``morphism'' by ``morphisms''. (U. Hartl)
p. 268,
l. $-7$
Insert ``if'' after ``In fact,''. (U. Hartl)
p. 270,
Line 17
Remove "it". (F. Gispert Sánchez)
p. 272,
Line 12
Replace "subscheme) structure" with "subscheme structure)". (F. Gispert Sánchez)
p. 273,
Line -14
Add "is" before "constructible". (F. Gispert Sánchez)
p. 274,
Line 9
Replace "$E\subseteq \pi^{-1}(\mathcal{P})$" with "$\overline{E}\supseteq \pi^{-1}(\mathcal{P})$". (If $\pi(\mathfrak{p})=p$ with $p\in\mathcal{P}$, then $\pi(\mathfrak{m})=p$ for all closed points $\mathfrak{m}$ which are specializations of $\mathfrak{p}$, as $\pi$ is continuous. Since all such closed points belong to $E$ and $R$ is a finitely-generated $\mathbb{Z}$-algebra and, in particulalr, Jacobson, we conclude that $\mathfrak{p}\in\overline{E}$.) (F. Gispert Sánchez)
p. 274,
Line 4
Replace ``suffice'' by ``suffices''. (U. Görtz)
p. 275,
Line 21
Replace "Corollary 10.85" with "Theorem 10.84" (we want to apply it to $\mathscr{H}$, not to $\mathscr{O}_X$). (F. Gispert Sánchez)
p. 276,
Line 20
Add "of" between "is" and "finite type". (F. Gispert Sánchez)
p. 277,
Line 10
Replace "Corollary 5.12" with "Corollary 5.17". (F. Gispert Sánchez)
p. 277,
Line 21
Add that $S$ is noetherian. (F. Gispert Sánchez)
p. 278,
Lines 21-26 (last paragraph of the proof of thm. 10.97)
Replace "$X_\xi$" with "$X_\eta$" (three times). Moreover, if $U$ is the non-empty open subset of $S$ which we are considering, the last equation holds for $v\in V=Y\cap f^{-1}(U)$ (not all $Y$). (F. Gispert Sánchez)
p. 281,
Line 25 (ex. 10.22)
Replace "is" with "be its". (F. Gispert Sánchez)
p. 283,
Line -14 (ex. 10.34)
Replace "inductive limit" with "inductive system". (F. Gispert Sánchez)
p. 287,
Line 3
Replace "$S$" by "$X$". (F. Gispert Sánchez)
p. 288,
Line 2
Replace "$\binom{r+n-1}{r}$" with "$\binom{r+n-1}{n}$" (or "$\binom{r+n-1}{r-1}$"). (F. Gispert Sánchez)
p. 289,
Prop. 11.3
In the statement of the proposition (and in its proof), one should add parentheses in order to emphasize that the target of the isomorphism is $\Gamma(T, (h^* \mathscr E)^\vee)$. (P. Hartwig)
p. 291,
Line 9
Remove the extra parenthesis in "$\mathscr{S}(V/X))$". (F. Gispert Sánchez)
p. 293,
Line 9
Replace "1-cocycle" with "1-cocycles". (F. Gispert Sánchez)
p. 293,
Line -14
Replace "1-cocycle" with "1-cocycles". (F. Gispert Sánchez)
p. 295,
Lines -2, -3, -5
Replace $\mathscr Isom(\mathscr E, \mathscr O_X^n)$ by $\mathscr Isom(\mathscr O_X^n, \mathscr E)$. (A. Schiller)
p. 295,
Line 5
Add somewhere that $\varphi$ is the map $G'\to G$ in the short exact sequence (11.5.5). (F. Gispert Sánchez)
p. 296,
Line -3
The discussion in Example 11.42 only considers the noetherian case. (The result is true in general, see e.g. Stacks project 0BCH.)
Also, add "ring" after "factorial" (alternatively, remove "a" before).
(F. Gispert Sánchez)
p. 298,
Line 6
We can only conclude that the immersion is locally of finite presentation. (F. Gispert Sánchez)
p. 299,
Line 6
The sheaf $\mathscr{R}_X$ has not been defined (it is the sheaf given by $U\mapsto R(U)$), and maybe should not a priori be called a ``constant sheaf'' here. (F. Gispert Sánchez)
p. 299,
6th line after Definition 11.19
TeX: $\mathop{\rm Div}(X)$ should be upright ()
p. 300,
Line 3
The mapping $U\mapsto {\rm Frac}(\Gamma(U,\mathscr O_X))$ is not a presheaf in general (rather, one should consider the localization with respect to elements which are non-zero divisors in every stalk). See Kleiman, Misconceptions about $K_X$. Enseign. Math. (2) 25 (1979), no. 3-4, 203--206 (1980), for a detailed discussion. (P. Hartwig)
p. 303,
Line 3
Replace ``detailed'' by ``detail''. (J. Calabrese)
p. 305,
Line -3
Replace ``for every maximal point of ${\rm Supp} D$'' by ``for every maximal point $\eta$ of ${\rm Supp} D$''. (T. Wedhorn)
p. 305,
Prop. 11.32
Replace the definition of ``regular'' given in parentheses by ``i.e., the associated homomorphism $\mathscr O_X \rightarrow \mathscr L$ is injective''. (K. Kidwell)
p. 305,
Line 27
Replace "$\mathscr{O}$" with "$\mathscr{O}_X$". (F. Gispert Sánchez)
p. 305,
Line -8 (Lemma 11.33)
The notation for the codimension is different from the notation used in chapter 5. (F. Gispert Sánchez)
p. 305,
Line 19 (displayed bijection)
Replace "cartier" with "Cartier". (F. Gispert Sánchez)
p. 306,
Line -16
Replace "$\mathscr{O}_{X,c}$" with "$\mathscr{O}_{X,C}$". (F. Gispert Sánchez)
p. 308,
Prop. 11.40
The proposition is not true as it stands (a counterexample is given by $X$ the plane with a fattened origin, and $Z$ the origin). It is correct with the additional assumption that $U$ be schematically dense in $X$ (use the characterization in Lemma 9.23 (ii) to conclude that the exactness at $Z^1(X)$ of the corresponding sequence of groups of cycles yields the exactness at ${\rm Cl}(X)$ of the sequence in the proposition). (B. Smithling)
p. 308,
Line 13
Replace $U$ by $U_i$ (twice). (B. Smithling)
p. 309,
Line -4ff
Replace ``as product $f_1f_2\dots f_r$, where $f_i \in S$ are irreducible homogeneous polynomials'' by ``as product $f_1^{d_1}f_2^{d_2}\dots f_r^{d_r}$, where $f_i \in S$ are irreducible homogeneous polynomials and $d_i \in {\mathbb Z}$'' and replace ``$Z\colon {\mathcal R} \to Z^1({\mathbb P}^n_k), f \mapsto \sum_i [V_+(f_i)]$'' by ``$Z\colon {\mathcal R} \to Z^1({\mathbb P}^n_k), f \mapsto \sum_i d_i[V_+(f_i)]$''. (T. Wedhorn)
p. 313,
Line -6
Replace ``set'' by ``sets''. (P. Johnson)
p. 315,
Line -2
The notion of being "of pure dimension 1" has not been defined. It is defined in brackets in Proposition 15.1. The easiest fix here might be to replace it by ``equidimensional of dimension 1''. (F. Gispert Sánchez)
p. 319,
Line -13 (ex. 11.22 (a))
Replace "an" with "a". (F. Gispert Sánchez)
p. 321,
Line 24
Replace ``affine over $X$'' by ``affine over $Y$''. (P. Barik)
p. 321,
Line -16
Replace "a affine scheme" with "an affine scheme". (F. Gispert Sánchez)
p. 323,
Line 17
Replace $\otimes_{(A'\otimes_A B})\otimes$ by $\otimes_{(A'\otimes_A B)}$. (P. Barik)
p. 323,
Line -9
The (finite) covering $(U_i)_i$ of $X$ should be an affine open covering. (F. Gispert Sánchez)
p. 323,
Line 12
Replace $X' = \mathop{\rm Spec} B' \otimes_{\mathop{\rm Spec} B} \mathop{\rm Spec A}$ by $X' = \mathop{\rm Spec} B \otimes_{\mathop{\rm Spec} A} \mathop{\rm Spec A'}$. (P. Barik)
p. 323,
Line 8
In the last expression of 12.2.3 replace $Y'$ by $X'$. (P. Barik)
p. 324,
Line -17
Remove ``a'' at the end of the line. (K. Kidwell)
p. 324,
Line 2
Replace "$\mathscr{F}(X)$" with "$\mathscr{F}(U_i)$" (F. Gispert Sánchez)
p. 325,
Line -3
``Corollary 5.12'' should be ``Proposition 5.12''. (U. Hartl)
p. 328,
Prop. 12.18
The first formula is false (almost always, e.g. if $Y=\mathop{\rm Spec} \mathbb F_p$, $X=\mathop{\rm Spec} \mathbb F_{p^2}$, $X'=\mathop{\rm Spec} \mathbb F_{p^2}$). (Yehao Zhou)
p. 329,
Line 18
Replace "be" with "by". (F. Gispert Sánchez)
p. 332,
Lines 2 and 22
Both in the statement (twice) and in the proof (once) of Proposition 12.27, "$\mathscr{O}$" is used to denote "$\mathscr{O}_X$". (F. Gispert Sánchez)
p. 332,
Line -15
Replace ``Corollary 5.12'' by ``Proposition 5.12''. (S. Köbele)
p. 333,
Example 12.29
In several places, replace $t$ by $t'$. (S. Köbele)
p. 333,
Line -14
Replace $a_0$ by $a_n$. (S. Köbele)
p. 335,
Equation (12.8.1)
The middle term should be $\frac{f_j^{k+\ell}x_{\mathbf i}}{f_{\mathbf i}^k}$ instead of $\frac{f_j^{k+\ell}x_{\mathbf i}}{f_{\mathbf i}^r}$. (P. Barik)
p. 338,
Line 8
Add "be" between "let $\eta$" and "its generic point". (F. Gispert Sánchez)
p. 338,
Line 6
Replace "$H^1(\mathscr{O}_Y,\mathscr{F})$" with "$H^1(Y,\mathscr{F})$". (F. Gispert Sánchez)
p. 341,
Line 11
Add "be" before "its normalization". (F. Gispert Sánchez)
p. 342,
Line -12 (prop. 12.53)
Add that $X$ is integral. (F. Gispert Sánchez)
p. 344,
Line -11
Replace $f^{-1}(U)\subseteq V$ by $f^{-1}(V)\subseteq U$. (P. Barik)
p. 346,
Line -4
Replace "$\mathscr{O}_X$-module" with "$\mathscr{O}_X$-modules". (F. Gispert Sánchez)
p. 347,
Line 7
Add "is" before "not irreducible". (F. Gispert Sánchez)
p. 348,
Line -10
Add "be" before "its Stein factorization". (F. Gispert Sánchez)
p. 353,
Proof of Prop. 12.76
In the beginning of the proof, it would be useful to note that the inclusion $\mathop{\rm Isol}(B/A) \supseteq \mathop{\rm LocIsom}(B/\overline{A})$ follows easily from Lemma 12.75 (1) and going up for integral extensions, so that only the opposite inclusion is considered in the following.
In the second step, to see that $\mathfrak q'\in \mathop{\rm Isol(A'/A)}$, note that the existence of $U'$ shows that $\mathfrak q'$ is open in its fiber over $\mathop{\rm Spec} A$. By Lemma 12.72 it is therefore isolated, because the fiber is of finite type over $\kappa(\mathfrak q)$.
(F. Gispert Sánchez)
p. 356,
Lines 6 to 8
Replace "$W'$" with "$W$" and "$X'$" with "$X$" (three times altogether). Replace $f\mathscr O_Y$ by $\mathscr O_Y$ (twice). (F. Gispert Sánchez)
p. 357,
Proof of Thm. 12.73
In general, it is not true that $f'$ as defined in the book is of finite type; hence Cor. 12.78 cannot be applied directly. Instead, one can proceed as follows: Start the proof as in the book: the restriction of $c$ to ${\rm Isol}(c)$ is an open immersion, hence $h$ is an open immersion. Now approximate $X'$ by $X'_\mu$ which are affine of finite type over $Y$ (analogously to approximating $Z$ by $Z_\lambda$). Using Lemma 12.84, we may assume that $V'\rightarrow X'_\mu$ is an open immersion (for some fixed large $\mu$). Now replace $X'$ by $X'_\mu$ and continue as in the book: Define $Z$, apply 12.78 (which is now justified), observe that $V' \subseteq {\rm Isol}(X'/Z)$, and apply Lemma 12.84 again to approximations of $Z$. (Yehao Zhou)
p. 361,
Ex. 12.6
Replace isomporphism by isomorphism. (T. Keller)
p. 368,
Line -20
The element $f$ should be homogeneous. (U. Görtz)
p. 368,
Equation (13.1.1)
Replace $\mod f-1$ by $\mod (f-1)$ (A. Kaučikas)
p. 368,
Line -6
Replace ``ideal'' by ``ideals''. (U. Görtz)
p. 368,
Statement of Prop. 13.2 (2)
We must assume that $0\notin S$ and that $S$ contains an element of $A_+$. (K. Kidwell)
p. 368,
Prop. 13.2 (3)
Replace ``with all relevant prime ideals'' by ``with the intersection of all relevant prime ideals''. (K. Kidwell)
p. 370,
Line 10
$f \in rad(g)_+$ should read $g \in rad(f)_+$. (F. Gispert Sánchez/N. Pflueger)
p. 375,
Line -3
Replace definition of $\sigma$ by ``$\sigma(t'):= t / f^n \in \Gamma_*(\mathscr F)_{(f)}$''. (P. Johnson)
p. 376,
Line -10 (thm. 13.20, displayed equation, under the arrow)
Replace "$\mathscr{F} \mapsfrom \Gamma_{*}(\mathscr{F})$" with "$\Gamma_{*}(\mathscr{F}) \mapsfrom \mathscr{F}$". (F. Gispert Sánchez)
p. 377,
Line 15
Replace ``$n \ge 0$'' by ``$n\ge n_0$''. (P. Johnson)
p. 377,
Proposition 13.22 (statement and proof)
The symbol $n$ is used for two different things: the number of generators of $A_+$ and as an index for $\mathscr{F}(n)$. (F. Gispert Sánchez)
p. 378,
line 2
Replace "on" with "one." (N. Pflueger)
p. 379,
Prop. 13.28
In the first line of the statement of the proposition, replace ``modules'' by ``module''. (P. Johnson)
p. 379,
Line -2
Replace "$\varphi$" with "$\varphi_i$". (F. Gispert Sánchez)
p. 379,
Line -9
The meaning of the symbol $\pi$ should be stated again. Both in the statement of proposition 13.28 and at the end of the proof (in the next page), I would write "$g^*_{\mathscr{L}}(\mathscr{O}_X(n)\otimes\pi^*(\mathscr{L}^{\otimes n}))$" with the extra parentheses (or, alternatively, replace "$\pi$" with "$\pi'$"). (F. Gispert Sánchez)
p. 379,
Line -1
The domain and codomain of $g_i$ are swapped: switch $\mathscr{A}_i$ and $\mathscr{A}'_i$. (F. Gispert Sánchez)
p. 380,
Line 17
Add "be" before "the structure morphism". (F. Gispert Sánchez)
p. 380,
Line 8
Replace "$\mathscr{O}(n)$" with "$\mathscr{O}_X(n)$". (F. Gispert Sánchez)
p. 380,
Line 6
Add "be" before "the structure morphism". (F. Gispert Sánchez)
p. 380,
Line 3
Replace "$f_j^{-1}$" with "$f_j^{-n}$". (F. Gispert Sánchez)
p. 382,
Line -12
Replace $\alpha_i$ by $\alpha_j$. (T. Keller)
p. 382,
Line 21
Replace "$\mathscr{O}^{n+1}$" with "$\mathscr{O}^{n+1}_X$". (F. Gispert Sánchez)
p. 382,
Lines 15, 18
Replace $\mathbb P^{n+1}$ by $\mathbb P^n$ (three times). (K. Kidwell)
p. 383,
Line 10
Replace "$R$-modules" with "$R$-module". (F. Gispert Sánchez)
p. 388,
Line -6, Line -3
Add that $f$ is homogeneous. (F. Gispert Sánchez)
p. 390,
Line -9
Replace "$(i\times \id_{S'}) \mathscr{O}_{P'}(1)$" with "$(i\times \id_{S'})^* \mathscr{O}_{P'}(1)$". (F. Gispert Sánchez)
p. 390,
Line -16
Omit the statement in parentheses. It is not true that the existence of an ample line bundle implies properness. (P. Hartwig)
p. 391,
Line 2
Replace "(the globalization) of" with "(the globalization of)". (F. Gispert Sánchez)
p. 392,
Line -17
Remove "be". (F. Gispert Sánchez)
p. 393,
Line 8
Replace "send" with "sent". (F. Gispert Sánchez)
p. 393,
Line -15
Replace "$i'\colon X \hookrightarrow P'$" with "$i'\colon X \to P'$" (as $i'$ is not necessarily an immersion, only $i$ is). (F. Gispert Sánchez)
p. 393,
Lines -8 and -7
Replace "(2)" with "(1)" (twice). (F. Gispert Sánchez)
p. 394,
Line -15
Replace "$n\geq n_0+m_0$" with "$n\geq d+m_0$". (F. Gispert Sánchez)
p. 394,
Line 20
Add that "$S=\Spec R$" somewhere ($R$ has not been defined). (F. Gispert Sánchez)
p. 394/395,
(13.13)
In line $-8$, replace ``non-zero'' by ``regular''. At the end of that paragraph, add a reference to Prop. 11.32 (in addition to Cor. 11.28). At the beginning of page 395, add the assumption that $X$ be integral (to ensure that all non-zero global sections of a line bundle are regular). (K. Kidwell)
p. 395,
Def. 13.60
Insert $\mathscr L$ after $\mathscr O_X$-module. (P. Johnson)
p. 396,
Line -6
Replace "$g^{-1}(X_s)$" with "$(g')^{-1}(X_s)$". (F. Gispert Sánchez)
p. 396,
Line -1
Add the missing closing parenthesis at the end. (F. Gispert Sánchez)
p. 398,
Lines -6 & -2 (def./prop. 13.68)
Replace "a quasi-coherent $\mathscr{O}_X$-module $\mathscr{E}$" with "a quasi-coherent $\mathscr{O}_S$-module $\mathscr{E}$" (twice). (F. Gispert Sánchez)
p. 398,
Line -9
Replace $Y\backslash \varepsilon(S)$ by $C\backslash \varepsilon(S)$. (U. Görtz)
p. 404,
Line 19
Replace "by Corollary 13.42" with "by Example 13.69". (F. Gispert Sánchez)
p. 409,
Diagram (13.19.1)
In the top right corner, replace $\mathop{\rm Bl}\nolimits_X(Z)$ by $\mathop{\rm Bl}\nolimits_Z(X)$. (J. Watterlond)
p. 416,
Line 19
Replace "morphisms" with "morphism". (F. Gispert Sánchez)
p. 418,
Line -6 (ex. 13.2 (a))
Replace "(resp. bijective)" with "(resp. surjective)". (F. Gispert Sánchez)
p. 419,
Line 1 (ex. 13.3)
Replace "$A$-modules" with "$A$-module". (F. Gispert Sánchez)
p. 423,
Line 11
Replace ``morphisms'' by ``morphism''. (K. Kidwell)
p. 426,
Line -2
Replace ``$\mathop{\rm Spec} R$'' by ``$Y$''. (T. Wedhorn)
p. 426,
Line 16 (cor. 14.12)
Replace "a morphism" with "morphisms". (F. Gispert Sánchez)
p. 427,
Proof of prop. 14.16
In the proof, $X$ is replaced by $\Spec \mathscr{O}_{X,x}$ and $f$ is replaced by the composition of $f$ with the canonical morphism $\Spec \mathscr{O}_{X,x} \to X$ without saying so. It would be useful to state this explicitly. (F. Gispert Sánchez)
p. 428,
Lemma 14.19
Replace ``such'' by ``such that''. (U. Görtz)
p. 428,
Proposition 14.20, Lemma 14.21
The lemma is incorrect as stated, because the reduction to the local case does not work as claimed. It should be replaced by the following: (1) Let $A$ be a noetherian ring, let $B$ be a noetherian $A$-algebra, and let $M$ be a $B$-module of finite type which is flat over $A$. Let $f\in B$ such that for every maximal ideal $\mathfrak M\subset B$, multiplication by $f$ is an injection $M/(\mathfrak M\cap A) \rightarrow M/(\mathfrak M\cap A)$. Then $M/fM$ is flat over $A$. (2) With the techniques of Chapter 10 the hypothesis ``noetherian'' can be replaced by suitable conditions like ``finite presentation''. See also MathOverflow and Matsumura, Commutative Ring Theory, Thm. 22.6.
To avoid the additional difficulty for non-noetherian rings, in the statement of the proposition the assumption that $S$ and $X$ be noetherian should be added. Assuming that $S=\mathop{\rm Spec} A$, $X = \mathop{\rm Spec B}$, the injectivity assertion means that for all maximal ideals $\mathfrak m\subset A$, $f\not\in \mathfrak mB$; it follows that $f\not\in (\mathfrak M \cap A)B$ for all maximal ideals $\mathfrak M\subset B$, so that the lemma (statement (1) of the previous paragraph) can be applied.
In the proof of Theorem 14.22 (in the non-noetherian case) a version of the Lemma as alluded to in (2) above is required.
(U. Görtz)
p. 428,
Proof of prop. 14.17
Here, Proposition B.70 (6) is not enough because $X$ is not assumed to be locally noetherian. Thus, we need a slightly different result: If $f$ is flat, then it is even faithfully flat (since it is closed and dominant). Now use that if $A\subseteq B$ are domains with the same field of fractions and $B$ is faithfully flat over $A$, then $A=B$. (Say $\frac as\in B$ for $a, s\in A$. Then $a\in sB\cap A = sA$ by Matsumura, Commutative Ring Theory, Thm. 7.5 (ii), so $\frac as\in A$.) (F. Gispert Sánchez)
p. 434,
Line -14
Add "the" between "If $y$ is not" and "closed point". (F. Gispert Sánchez)
p. 435,
Line -17
Replace "morphism" with "morphisms". (F. Gispert Sánchez)
p. 443,
Line 3
Replace "a open immersion" with "an open immersion". (F. Gispert Sánchez)
p. 443,
Line -16
Add "a" between "Let $\mathbf{P}$ be" and "property". (F. Gispert Sánchez)
p. 447,
Line 10
Replace "$(\mathscr{G},\psi)$" with "$(\mathscr{G}',\psi)$". (F. Gispert Sánchez)
p. 447,
Line 10
Replace $\mathscr G$ by $\mathscr G'$. (K. Kidwell)
p. 449,
Line 5
Replace "$q=p_1\circ p=p_2\circ p$" with "$q=p\circ p_1=p\circ p_2$". (F. Gispert Sánchez)
p. 452,
Line -10
Replace "homomorphism" with "homomorphisms". (F. Gispert Sánchez)
p. 453,
Line 14
The reference to Theorem 14.17 is wrong. It should refer to Theorem 14.70. (F. Gispert Sánchez)
p. 454,
Line 2
Replace "or fppf-sheaves of sheaves" with "or fppf-sheaves or sheaves". (F. Gispert Sánchez)
p. 454,
Line -17
Replace "an morphism" with "a morphism". (F. Gispert Sánchez)
p. 455,
Line -10
Replace "$G_{S'}$" with "$G_{|S'}$". (F. Gispert Sánchez)
p. 457,
Proof of Thm. 14.83
With the given reference to Morita equivalence in (8.12) the proof covers only the case of finite-dimensional vector spaces. The theorem follows from this because every finite-dimensional $k'$-subvector space of a given $V'$ is contained in a $\Gamma$-invariant finite-dimensional $k'$-subvector space of $V'$, so we can write $V'$ as the union of its finite-dimensional $\Gamma$-invariant subvector spaces, and get the result for $V'$ from the finite-dimensional case. Also it should maybe be stated that for the last assertion of the theorem (taking invariants is a quasi-inverse), it is enough to show - given that we have proved that base change is an equivalence of the two categories - that $(V\otimes k')^\Gamma = V$, which is clear. (U. Görtz)
p. 457,
Line 3
Replace "$\gamma(a_\delta)$" with "$\gamma(b_\delta)$". (F. Gispert Sánchez)
p. 460,
Diagram (14.22.1), definition of $c(\gamma)$
It looks like if we want $c$ to be 1-cocycle, then $c(\gamma)$ should be $\gamma_Y\circ\gamma^{-1}$ instead of $\gamma^{-1}\circ\gamma_Y$ as you defined using the diagram. (Han Zhou)
p. 468,
Line -11
Replace ``Lemma 14.106 2'' by ``Lemma 14.106 (2)''. (U. Görtz)
p. 478,
Line -11/Page 583, Line 2
The reference [AK] should point to the following article: Altman, Allen B.; Kleiman, Steven L. Compactifying the Picard scheme. Adv. in Math. 35 (1980), no. 1, 50-112. (P. Hartwig)
p. 485,
Prop. 15.1 (ii)
Add ``and none of the $X_i$ consists of only one point''. (U. Görtz)
p. 487,
Line 11
Replace the title of the segment by ``Morphisms from spectra of valuation rings to schemes''. (U. Görtz)
p. 488,
Prop. 15.7
Rephrase the statement of the Proposition to indicate that the equality $g(\eta) = y$ can/should be understood in the schematic sense, i.e., that $g$ extends the morphism $\mathop{\rm Spec} K \rightarrow Y$ coming from the inclusion $\kappa(y)\subseteq K$. (U. Görtz)
p. 488,
Line 11
Replace ``we can in addition assume that the ring $A$ is noetherian'' by ``then the ring $A$ is noetherian''. (U. Görtz)
p. 497,
Line 13
Replace ``If $C$ is a separated curve over a field,'' by ``If $C$ is a separated curve over a field and $U$ is chosen affine,''. (T. Wedhorn)
p. 501,
Line 9
Replace ``morpism'' by ``morphism''. (J. Scarfy)
p. 514,
Line -7
Replace ``$Y = \mathop{\rm Spec} B[1/d_{I,J}]$'' by ``$Y_{I,J} = \mathop{\rm Spec} B[1/d_{I,J}]$''. (T. Wedhorn)
p. 528,
Line 14
Replace ``$V_+(p)\in\mathbb P^3_k$'' by ``$V_+(p)\subset\mathbb P^3_k$''. (U. Görtz)
p. 528,
Line -18
Replace $T_2T_3^3$ by $T_2T_3^2$. (U. Görtz)
p. 534,
Line 11
Replace the definition of $g$ by ``$g := f \circ (x \times \mathop{\rm id}\nolimits_Y) \circ p_2$''. (K. Kidwell)
p. 540,
Exercise 16.7
As a connected component $G'$ has not necessarily a rational point, it is not geometrically connected in general (and in particular not geometrically irreducible). The exercise should be reformulated as follows: Let $k$ be a field and let $G$ be a $k$-group schemes locally of finite type. Show that every connected component $G'$ of $G$ is irreducible and of finite type. Show that the geometric number of connected components of $G'$ is equal to the geometric number of irreducible components of $G'$. For $k = {\mathbb Q}$ and $G = \mu_p$ (Exercise 16.6) for a prime number $p$ show that $G$ has two connected components and that the geometric number of connected components of $G$ is $p$. (B. Conrad)
p. 546,
Line -10/-9
Replace ``left'' by ``right'' and ``right'' by ``left''. (D. Heiss)
p. 549,
Line -2
The rank of a free module over the zero ring is not uniquely determined, so this case should be excluded. (P. Hartwig)
p. 552,
Line 7 (ex. B.17)
Replace "$\mathfrak{m}M\neq M$" with "$\mathfrak{m}M=M$". (F. Gispert Sánchez)
p. 560,
Prop. B.55
Add the hypothesis that $A$ is noetherian (cf. [Atiyah-Macdonald], Prop. 5.17). (Akira Masuoka)
p. 561,
Definition B.58
In the second line of the definition, $r$ should be replaced by $n$. (P. Hartwig)
p. 563,
Prop. B69 (2)
The assumption that the extension be algebraic is not required, see [BouAC] VI § 1.2 Cor. to Thm. 2. (Akira Masuoka)
p. 565,
Remark B.75 (2)
Replace the reference to B.70 (2) by B.70 (3). (Akira Masuoka)
p. 566,
Prop. B.81 (2), Prop. B.82
In both cases $\mathop{\rm depth}\nolimits_A(\mathfrak a)$ needs to be replaced by $\mathop{\rm depth}(\mathfrak a, A)$ (the length of a maximal $A$-regular sequence of elements in $\mathfrak a$, and this symbol needs to be defined). (Akira Masuoka)
p. 574+575,
Add (IND) for faithfully flat and surjective (cf. EGA IV 8.10.5 (vi)). (Y. Zaehringer)
p. 603,
Line 17
Replace ``Brauer-Severy'' by ``Brauer-Severi''. (J. Calabrese)