Update to Lean 4.22.0 and intermediate lean versions

lean4/check_docstrings.lean

@@ -50,10 +50,18 @@ def getSource (n : Name) : CoreM <| Option (Name × DeclarationRange) := do
   let .some mod ← Lean.findModuleOf? n | return none
   return some (mod, ranges.range)
 
+def escapeDocstring (s : String) : String := Id.run do
+  -- Add a space after `<` to ensure it isn't treated as HTML by VSCode's syntax highlighting.
+  match s.splitOn "<" with
+  | [] => s
+  | x :: parts =>
+    return x ++ (String.join <| parts.map fun p =>
+      if (p.get? 0 |>.map Char.isAlpha).getD false then s!"< {p}" else s!"<{p}")
+
 /-- Return true if the entry is ok -/
 def checkEntry (entry : InformalJsonEntry) : CoreM EntryResult := do
   let doc? := (← Lean.findDocString? (← getEnv) entry.problem_name).map String.trim
-  if doc? = some entry.informal_statement.trim then
+  if doc? = some (escapeDocstring entry.informal_statement.trim) then
     return .docMatching
   else if let .some doc := doc? then
     let srcInfo ← getSource entry.problem_name
@@ -62,7 +70,7 @@ def checkEntry (entry : InformalJsonEntry) : CoreM EntryResult := do
       \nPlease either change this docstring or modify the JSON file. Be careful to escape LaTeX when writing JSON.\
       \nThe JSON file currently contains:\
       \n\
-      \n{entry.informal_statement.trim}\
+      \n{escapeDocstring entry.informal_statement.trim}\
       \n\
       \nWhile the docstring contains:
       \n\

lean4/lake-manifest.json

@@ -5,27 +5,27 @@
    "type": "git",
    "subDir": null,
    "scope": "",
-   "rev": "5269898d6a51d047931107c8d72d934d8d5d3753",
+   "rev": "79e94a093aff4a60fb1b1f92d9681e407124c2ca",
    "name": "mathlib",
    "manifestFile": "lake-manifest.json",
-   "inputRev": "v4.17.0",
+   "inputRev": "v4.22.0",
    "inherited": false,
    "configFile": "lakefile.lean"},
   {"url": "https://github.com/leanprover-community/plausible",
    "type": "git",
    "subDir": null,
    "scope": "leanprover-community",
-   "rev": "c708be04267e3e995a14ac0d08b1530579c1525a",
+   "rev": "b100ad4c5d74a464f497aaa8e7c74d86bf39a56f",
    "name": "plausible",
    "manifestFile": "lake-manifest.json",
-   "inputRev": "main",
+   "inputRev": "v4.22.0",
    "inherited": true,
    "configFile": "lakefile.toml"},
   {"url": "https://github.com/leanprover-community/LeanSearchClient",
    "type": "git",
    "subDir": null,
    "scope": "leanprover-community",
-   "rev": "0c169a0d55fef3763cfb3099eafd7b884ec7e41d",
+   "rev": "99657ad92e23804e279f77ea6dbdeebaa1317b98",
    "name": "LeanSearchClient",
    "manifestFile": "lake-manifest.json",
    "inputRev": "main",
@@ -35,57 +35,57 @@
    "type": "git",
    "subDir": null,
    "scope": "leanprover-community",
-   "rev": "0447b0a7b7f41f0a1749010db3f222e4a96f9d30",
+   "rev": "eb164a46de87078f27640ee71e6c3841defc2484",
    "name": "importGraph",
    "manifestFile": "lake-manifest.json",
-   "inputRev": "main",
+   "inputRev": "v4.22.0",
    "inherited": true,
    "configFile": "lakefile.toml"},
   {"url": "https://github.com/leanprover-community/ProofWidgets4",
    "type": "git",
    "subDir": null,
    "scope": "leanprover-community",
-   "rev": "799f6986de9f61b784ff7be8f6a8b101045b8ffd",
+   "rev": "1253a071e6939b0faf5c09d2b30b0bfc79dae407",
    "name": "proofwidgets",
    "manifestFile": "lake-manifest.json",
-   "inputRev": "v0.0.52",
+   "inputRev": "v0.0.68",
    "inherited": true,
    "configFile": "lakefile.lean"},
   {"url": "https://github.com/leanprover-community/aesop",
    "type": "git",
    "subDir": null,
    "scope": "leanprover-community",
-   "rev": "56a2c80b209c253e0281ac4562a92122b457dcc0",
+   "rev": "1256a18522728c2eeed6109b02dd2b8f207a2a3c",
    "name": "aesop",
    "manifestFile": "lake-manifest.json",
-   "inputRev": "master",
+   "inputRev": "v4.22.0",
    "inherited": true,
    "configFile": "lakefile.toml"},
   {"url": "https://github.com/leanprover-community/quote4",
    "type": "git",
    "subDir": null,
    "scope": "leanprover-community",
-   "rev": "95561f7a5811fae6a309e4a1bbe22a0a4a98bf03",
+   "rev": "917bfa5064b812b7fbd7112d018ea0b4def25ab3",
    "name": "Qq",
    "manifestFile": "lake-manifest.json",
-   "inputRev": "master",
+   "inputRev": "v4.22.0",
    "inherited": true,
    "configFile": "lakefile.toml"},
   {"url": "https://github.com/leanprover-community/batteries",
    "type": "git",
    "subDir": null,
    "scope": "leanprover-community",
-   "rev": "efcc7d9bd9936ecdc625baf0d033b60866565cd5",
+   "rev": "240676e9568c254a69be94801889d4b13f3b249f",
    "name": "batteries",
    "manifestFile": "lake-manifest.json",
-   "inputRev": "main",
+   "inputRev": "v4.22.0",
    "inherited": true,
    "configFile": "lakefile.toml"},
   {"url": "https://github.com/leanprover/lean4-cli",
    "type": "git",
    "subDir": null,
    "scope": "leanprover",
-   "rev": "e7fd1a415c80985ade02a021172834ca2139b0ca",
+   "rev": "c682c91d2d4dd59a7187e2ab977ac25bd1f87329",
    "name": "Cli",
    "manifestFile": "lake-manifest.json",
    "inputRev": "main",

lean4/lakefile.lean

@@ -6,7 +6,7 @@ package «putnam» where
   leanOptions := #[
     ⟨`autoImplicit, false⟩
   ]
-require mathlib from git "https://github.com/leanprover-community/mathlib4" @ "v4.17.0"
+require mathlib from git "https://github.com/leanprover-community/mathlib4" @ "v4.22.0"
 
 @[default_target]
 lean_lib «putnam» where

lean4/lean-toolchain

@@ -1 +1 @@
-leanprover/lean4:v4.17.0
+leanprover/lean4:v4.22.0

lean4/src/putnam_1967_a3.lean

@@ -5,7 +5,7 @@ open Polynomial
 abbrev putnam_1967_a3_solution : ℕ := sorry
 -- 5
 /--
-Consider polynomial forms $ax^2-bx+c$ with integer coefficients which have two distinct zeros in the open interval $0<x<1$. Exhibit with a proof the least positive integer value of $a$ for which such a polynomial exists.
+Consider polynomial forms $ax^2-bx+c$ with integer coefficients which have two distinct zeros in the open interval $0< x<1$. Exhibit with a proof the least positive integer value of $a$ for which such a polynomial exists.
 -/
 theorem putnam_1967_a3 :
     IsLeast

lean4/src/putnam_1969_b4.lean

@@ -10,7 +10,7 @@ theorem putnam_1969_b4
     --Note: the problem doesn't say what regularity conditions we should impose on `Γ` - hopefully continuity is enough.
     (Γ_cts : ContinuousOn Γ (Set.Icc 0 1))
     (hΓ : eVariationOn Γ (Set.Icc 0 1) = 1) :
-    letI : Module.Oriented ℝ (EuclideanSpace ℝ (Fin 2)) (Fin 2) := ⟨Basis.orientation <| Pi.basisFun _ _⟩
+    letI : Module.Oriented ℝ (EuclideanSpace ℝ (Fin 2)) (Fin 2) := ⟨Module.Basis.orientation <| Pi.basisFun _ _⟩
     letI : Fact (Module.finrank ℝ (EuclideanSpace ℝ (Fin 2)) = 2) := ⟨finrank_euclideanSpace_fin⟩
     ∃ (a b c d : EuclideanSpace ℝ (Fin 2)), Γ '' (Set.Icc 0 1) ⊆
       convexHull ℝ {a, b, c, d} ∧ dist a b * dist b c = 1/4 ∧

lean4/src/putnam_1984_b2.lean

@@ -5,7 +5,7 @@ open Topology Filter Nat
 abbrev putnam_1984_b2_solution : ℝ := sorry
 -- 8
 /--
-Find the minimum value of $(u-v)^2+(\sqrt{2-u^2}-\frac{9}{v})^2$ for $0<u<\sqrt{2}$ and $v>0$.
+Find the minimum value of $(u-v)^2+(\sqrt{2-u^2}-\frac{9}{v})^2$ for $0< u<\sqrt{2}$ and $v>0$.
 -/
 theorem putnam_1984_b2
     (f : ℝ → ℝ → ℝ)

lean4/src/putnam_1989_b6.lean

@@ -4,7 +4,7 @@ open Nat Filter Topology Set ProbabilityTheory
 
 -- Note: uses (ℝ → ℝ) instead of (Set.Icc 0 1 → ℝ)
 /--
-Let $(x_1,x_2,\dots,x_n)$ be a point chosen at random from the $n$-dimensional region defined by $0<x_1<x_2<\dots<x_n<1$. Let $f$ be a continuous function on $[0,1]$ with $f(1)=0$. Set $x_0=0$ and $x_{n+1}=1$. Show that the expected value of the Riemann sum $\sum_{i=0}^n (x_{i+1}-x_i)f(x_{i+1})$ is $\int_0^1 f(t)P(t)\,dt$, where $P$ is a polynomial of degree $n$, independent of $f$, with $0 \leq P(t) \leq 1$ for $0 \leq t \leq 1$.
+Let $(x_1,x_2,\dots,x_n)$ be a point chosen at random from the $n$-dimensional region defined by $0< x_1< x_2<\dots< x_n<1$. Let $f$ be a continuous function on $[0,1]$ with $f(1)=0$. Set $x_0=0$ and $x_{n+1}=1$. Show that the expected value of the Riemann sum $\sum_{i=0}^n (x_{i+1}-x_i)f(x_{i+1})$ is $\int_0^1 f(t)P(t)\,dt$, where $P$ is a polynomial of degree $n$, independent of $f$, with $0 \leq P(t) \leq 1$ for $0 \leq t \leq 1$.
 -/
 theorem putnam_1989_b6
     (n : ℕ) [NeZero n]

lean4/src/putnam_1991_a3.lean

@@ -6,7 +6,7 @@ open Filter Topology
 abbrev putnam_1991_a3_solution : Set (Polynomial ℝ) := sorry
 -- {p : Polynomial ℝ | p.degree = 2 ∧ (∃ r1 r2 : ℝ, r1 ≠ r2 ∧ p.eval r1 = 0 ∧ p.eval r2 = 0)}
 /--
-Find all real polynomials $p(x)$ of degree $n \geq 2$ for which there exist real numbers $r_1<r_2<\cdots<r_n$ such that
+Find all real polynomials $p(x)$ of degree $n \geq 2$ for which there exist real numbers $r_1< r_2<\cdots< r_n$ such that
 \begin{enumerate}
 \item $p(r_i)=0, \qquad i=1,2,\dots,n$, and
 \item $p'(\frac{r_i+r_{i+1}}{2})=0 \qquad i=1,2,\dots,n-1$,

lean4/src/putnam_1991_b6.lean

@@ -5,7 +5,7 @@ open Filter Topology
 noncomputable abbrev putnam_1991_b6_solution : ℝ → ℝ → ℝ := sorry
 -- (fun a b : ℝ => |Real.log (a / b)|)
 /--
-Let $a$ and $b$ be positive numbers. Find the largest number $c$, in terms of $a$ and $b$, such that $a^xb^{1-x} \leq a\frac{\sinh ux}{\sinh u}+b\frac{\sinh u(1-x)}{\sinh u}$ for all $u$ with $0<|u| \leq c$ and for all $x$, $0<x<1$. (Note: $\sinh u=(e^u-e^{-u})/2$.)
+Let $a$ and $b$ be positive numbers. Find the largest number $c$, in terms of $a$ and $b$, such that $a^xb^{1-x} \leq a\frac{\sinh ux}{\sinh u}+b\frac{\sinh u(1-x)}{\sinh u}$ for all $u$ with $0<|u| \leq c$ and for all $x$, $0< x<1$. (Note: $\sinh u=(e^u-e^{-u})/2$.)
 -/
 theorem putnam_1991_b6
   (a b : ℝ)

lean4/src/putnam_1993_b1.lean

@@ -3,7 +3,7 @@ import Mathlib
 abbrev putnam_1993_b1_solution : ℕ := sorry
 -- 3987
 /--
-Find the smallest positive integer $n$ such that for every integer $m$ with $0<m<1993$, there exists an integer $k$ for which $\frac{m}{1993}<\frac{k}{n}<\frac{m+1}{1994}$.
+Find the smallest positive integer $n$ such that for every integer $m$ with $0< m<1993$, there exists an integer $k$ for which $\frac{m}{1993}<\frac{k}{n}<\frac{m+1}{1994}$.
 -/
 theorem putnam_1993_b1 :
     IsLeast

lean4/src/putnam_1994_a1.lean

@@ -3,7 +3,7 @@ import Mathlib
 open Filter Topology
 
 /--
-Suppose that a sequence $a_1,a_2,a_3,\dots$ satisfies $0<a_n \leq a_{2n}+a_{2n+1}$ for all $n \geq 1$. Prove that the series $\sum_{n=1}^\infty a_n$ diverges.
+Suppose that a sequence $a_1,a_2,a_3,\dots$ satisfies $0< a_n \leq a_{2n}+a_{2n+1}$ for all $n \geq 1$. Prove that the series $\sum_{n=1}^\infty a_n$ diverges.
 -/
 theorem putnam_1994_a1
     (a : ℕ → ℝ)

lean4/src/putnam_1994_a5.lean

@@ -3,7 +3,7 @@ import Mathlib
 open Filter Topology
 
 /--
-Let $(r_n)_{n \geq 0}$ be a sequence of positive real numbers such that $\lim_{n \to \infty} r_n=0$. Let $S$ be the set of numbers representable as a sum $r_{i_1}+r_{i_2}+\cdots+r_{i_{1994}}$, with $i_1<i_2<\cdots<i_{1994}$. Show that every nonempty interval $(a,b)$ contains a nonempty subinterval $(c,d)$ that does not intersect $S$.
+Let $(r_n)_{n \geq 0}$ be a sequence of positive real numbers such that $\lim_{n \to \infty} r_n=0$. Let $S$ be the set of numbers representable as a sum $r_{i_1}+r_{i_2}+\cdots+r_{i_{1994}}$, with $i_1< i_2<\cdots< i_{1994}$. Show that every nonempty interval $(a,b)$ contains a nonempty subinterval $(c,d)$ that does not intersect $S$.
 -/
 theorem putnam_1994_a5
   (r : ℕ → ℝ)

lean4/src/putnam_1998_b2.lean

@@ -5,7 +5,7 @@ open Set Function Metric
 noncomputable abbrev putnam_1998_b2_solution : ℝ → ℝ → ℝ := sorry
 -- fun a b => if a > b then Real.sqrt (2*a^2 + 2*b^2) else 0
 /--
-Given a point $(a,b)$ with $0<b<a$, determine the minimum perimeter of a triangle with one vertex at $(a,b)$, one on the $x$-axis, and one on the line $y=x$.  You may assume that a triangle of minimum perimeter exists.
+Given a point $(a,b)$ with $0< b< a$, determine the minimum perimeter of a triangle with one vertex at $(a,b)$, one on the $x$-axis, and one on the line $y=x$.  You may assume that a triangle of minimum perimeter exists.
 -/
 theorem putnam_1998_b2
 (a b : ℝ)

lean4/src/putnam_2004_b6.lean

@@ -3,7 +3,7 @@ import Mathlib
 open Nat Topology Filter
 
 /--
-Let $\mathcal{A}$ be a non-empty set of positive integers, and let $N(x)$ denote the number of elements of $\mathcal{A}$ not exceeding $x$. Let $\mathcal{B}$ denote the set of positive integers $b$ that can be written in the form $b=a-a'$ with $a \in \mathcal{A}$ and $a' \in \mathcal{A}$. Let $b_1<b_2<\cdots$ be the members of $\mathcal{B}$, listed in increasing order. Show that if the sequence $b_{i+1}-b_i$ is unbounded, then $\lim_{x \to\infty} N(x)/x=0$.
+Let $\mathcal{A}$ be a non-empty set of positive integers, and let $N(x)$ denote the number of elements of $\mathcal{A}$ not exceeding $x$. Let $\mathcal{B}$ denote the set of positive integers $b$ that can be written in the form $b=a-a'$ with $a \in \mathcal{A}$ and $a' \in \mathcal{A}$. Let $b_1< b_2<\cdots$ be the members of $\mathcal{B}$, listed in increasing order. Show that if the sequence $b_{i+1}-b_i$ is unbounded, then $\lim_{x \to\infty} N(x)/x=0$.
 -/
 theorem putnam_2004_b6
   (A B : Set ℕ)

lean4/src/putnam_2006_a4.lean

@@ -7,7 +7,7 @@ noncomputable abbrev putnam_2006_a4_solution : ℕ → ℝ := sorry
 Let $S=\{1,2,\dots,n\}$ for some integer $n>1$. Say a permutation $\pi$ of $S$ has a \emph{local maximum} at $k \in S$ if
 \begin{enumerate}
 \item[(i)] $\pi(k)>\pi(k+1)$ for $k=1$;
-\item[(ii)] $\pi(k-1)<\pi(k)$ and $\pi(k)>\pi(k+1)$ for $1<k<n$;
+\item[(ii)] $\pi(k-1)<\pi(k)$ and $\pi(k)>\pi(k+1)$ for $1< k< n$;
 \item[(iii)] $\pi(k-1)<\pi(k)$ for $k=n$.
 \end{enumerate}
 (For example, if $n=5$ and $\pi$ takes values at $1,2,3,4,5$ of $2,1,4,5,3$, then $\pi$ has a local maximum of 2 at $k=1$, and a local maximum of 5 at $k=4$.) What is the average number of local maxima of a permutation of $S$, averaging over all permutations of $S$?

lean4/src/putnam_2013_a5.lean

@@ -4,7 +4,7 @@ open Function Set MeasureTheory
 
 -- Note: uses (Fin m → Fin m → Fin m → ℝ) instead of ensuring inputs are strictly increasing
 /--
-For $m \geq 3$, a list of $\binom{m}{3}$ real numbers $a_{ijk}$ ($1 \leq i<j<k \leq m$) is said to be \emph{area definite} for $\mathbb{R}^n$ if the inequality $\sum_{1 \leq i<j<k \leq m} a_{ijk} \cdot \text{Area}(\Delta A_iA_jA_k) \geq 0$ holds for every choice of $m$ points $A_1,\dots,A_m$ in $\mathbb{R}^n$. For example, the list of four numbers $a_{123}=a_{124}=a_{134}=1$, $a_{234}=-1$ is area definite for $\mathbb{R}^2$. Prove that if a list of $\binom{m}{3}$ numbers is area definite for $\mathbb{R}^2$, then it is area definite for $\mathbb{R}^3$.
+For $m \geq 3$, a list of $\binom{m}{3}$ real numbers $a_{ijk}$ ($1 \leq i< j< k \leq m$) is said to be \emph{area definite} for $\mathbb{R}^n$ if the inequality $\sum_{1 \leq i< j< k \leq m} a_{ijk} \cdot \text{Area}(\Delta A_iA_jA_k) \geq 0$ holds for every choice of $m$ points $A_1,\dots,A_m$ in $\mathbb{R}^n$. For example, the list of four numbers $a_{123}=a_{124}=a_{134}=1$, $a_{234}=-1$ is area definite for $\mathbb{R}^2$. Prove that if a list of $\binom{m}{3}$ numbers is area definite for $\mathbb{R}^2$, then it is area definite for $\mathbb{R}^3$.
 -/
 theorem putnam_2013_a5
 (m : ℕ)

lean4/src/putnam_2015_a5.lean

@@ -1,7 +1,7 @@
 import Mathlib
 
 /--
-Let $q$ be an odd positive integer, and let $N_q$ denote the number of integers $a$ such that $0<a<q/4$ and $\gcd(a,q)=1$. Show that $N_q$ is odd if and only if $q$ is of the form $p^k$ with $k$ a positive integer and $p$ a prime congruent to $5$ or $7$ modulo $8$.
+Let $q$ be an odd positive integer, and let $N_q$ denote the number of integers $a$ such that $0< a< q/4$ and $\gcd(a,q)=1$. Show that $N_q$ is odd if and only if $q$ is of the form $p^k$ with $k$ a positive integer and $p$ a prime congruent to $5$ or $7$ modulo $8$.
 -/
 theorem putnam_2015_a5
 (q : ℕ)

lean4/src/putnam_2017_a3.lean

@@ -4,7 +4,7 @@ open Topology Filter
 
 -- Note: uses (ℝ → ℝ) instead of (Set.Icc a b → Set.Ioi (0 : ℝ))
 /--
-Let $a$ and $b$ be real numbers with $a<b$, and let $f$ and $g$ be continuous functions from $[a,b]$ to $(0,\infty)$ such that $\int_a^b f(x)\,dx=\int_a^b g(x)\,dx$ but $f \neq g$. For every positive integer $n$, define $I_n=\int_a^b \frac{(f(x))^{n+1}}{(g(x))^n}\,dx$. Show that $I_1,I_2,I_3,\dots$ is an increasing sequence with $\lim_{n \to \infty} I_n=\infty$.
+Let $a$ and $b$ be real numbers with $a< b$, and let $f$ and $g$ be continuous functions from $[a,b]$ to $(0,\infty)$ such that $\int_a^b f(x)\,dx=\int_a^b g(x)\,dx$ but $f \neq g$. For every positive integer $n$, define $I_n=\int_a^b \frac{(f(x))^{n+1}}{(g(x))^n}\,dx$. Show that $I_1,I_2,I_3,\dots$ is an increasing sequence with $\lim_{n \to \infty} I_n=\infty$.
 -/
 theorem putnam_2017_a3
 (a b : ℝ)

lean4/src/putnam_2022_a4.lean

@@ -14,7 +14,7 @@ theorem putnam_2022_a4
     (X : ℕ → Ω → ℝ)
     (hX : ∀ i, Measurable (X i))
     (hX' : ∀ i, MeasureTheory.pdf.IsUniform (X i) (Set.Icc 0 1) ℙ)
-    (hX'' : iIndepFun (fun i => inferInstance) X)
+    (hX'' : iIndepFun X)
     (k : Ω → Set ℕ)
     /-
     If there is an `l` such that `X_l < X_{l+1}` then this is `Set.Iic l` for the smallest such `l`

lean4/src/putnam_2022_a6.lean

@@ -6,7 +6,7 @@ open Set
 abbrev putnam_2022_a6_solution : ℕ → ℕ := sorry
 -- (fun n : ℕ => n)
 /--
-Let $n$ be a positive integer. Determine, in terms of $n$, the largest integer $m$ with the following property: There exist real numbers $x_1,\dots,x_{2n}$ with $-1<x_1<x_2<\cdots<x_{2n}<1$ such that the sum of the lengths of the $n$ intervals $[x_1^{2k-1},x_2^{2k-1}],[x_3^{2k-1},x_4^{2k-1}],\dots,[x_{2n-1}^{2k-1},x_{2n}^{2k-1}]$ is equal to $1$ for all integers $k$ with $1 \leq k \leq m$.
+Let $n$ be a positive integer. Determine, in terms of $n$, the largest integer $m$ with the following property: There exist real numbers $x_1,\dots,x_{2n}$ with $-1< x_1< x_2<\cdots< x_{2n}<1$ such that the sum of the lengths of the $n$ intervals $[x_1^{2k-1},x_2^{2k-1}],[x_3^{2k-1},x_4^{2k-1}],\dots,[x_{2n-1}^{2k-1},x_{2n}^{2k-1}]$ is equal to $1$ for all integers $k$ with $1 \leq k \leq m$.
 -/
 theorem putnam_2022_a6
     (n : ℕ) (hn : 0 < n) :

lean4/src/putnam_2023_b4.lean

@@ -11,7 +11,7 @@ For a nonnegative integer $n$ and a strictly increasing sequence of real numbers
 \item[(a)] $f(t)$ is continuous for $t \geq t_0$, and is twice differentiable for all $t>t_0$ other than $t_1,\dots,t_n$;
 \item[(b)] $f(t_0)=1/2$;
 \item[(c)] $\lim_{t \to t_k^+} f'(t)=0$ for $0 \leq k \leq n$;
-\item[(d)] For $0 \leq k \leq n-1$, we have $f''(t)=k+1$ when $t_k<t<t_{k+1}$, and $f''(t)=n+1$ when $t>t_n$.
+\item[(d)] For $0 \leq k \leq n-1$, we have $f''(t)=k+1$ when $t_k< t< t_{k+1}$, and $f''(t)=n+1$ when $t>t_n$.
 \end{enumerate}
 Considering all choices of $n$ and $t_0,t_1,\dots,t_n$ such that $t_k \geq t_{k-1}+1$ for $1 \leq k \leq n$, what is the least possible value of $T$ for which $f(t_0+T)=2023$?
 -/

lean4/src/putnam_2024_b4.lean

@@ -33,6 +33,6 @@ theorem putnam_2024_b4
           a n k ω
         else
           a n k ω - 1)
-    (h₃ : ProbabilityTheory.iIndepFun inferInstance m.uncurry ℙ) :
+    (h₃ : ProbabilityTheory.iIndepFun m.uncurry ℙ) :
     Filter.Tendsto (fun n => (∫ ω, a n n ω : ℝ) / n) Filter.atTop (𝓝 putnam_2024_b4_solution) :=
   sorry