diff --git a/Aristotle/Basic.lean b/Aristotle/Basic.lean
index 99415d9..8845ac1 100644
--- a/Aristotle/Basic.lean
+++ b/Aristotle/Basic.lean
@@ -1 +1,15 @@
-def hello := "world"
+import Mathlib.Analysis.Meromorphic.Basic
+
+open MeromorphicOn Metric Real Set Classical
+
+variable
+  {𝕜 : Type*} [NontriviallyNormedField 𝕜]
+  {E : Type*} [NormedAddCommGroup E] [NormedSpace 𝕜 E]
+  {U : Set 𝕜} {f g : 𝕜 → E} {a : WithTop E} {a₀ : E}
+
+/-- Finite sums of meromorphic functions are meromorphic. -/
+@[fun_prop]
+theorem MeromorphicAt.sum {ι : Type*} {s : Finset ι} {f : ι → 𝕜 → E} {x : 𝕜}
+    (h : ∀ σ, MeromorphicAt (f σ) x) :
+    MeromorphicAt (∑ n ∈ s, f n) x := by
+  sorry
diff --git a/lake-manifest.json b/lake-manifest.json
index 91f6ace..ef01237 100644
--- a/lake-manifest.json
+++ b/lake-manifest.json
@@ -5,17 +5,17 @@
    "type": "git",
    "subDir": null,
    "scope": "leanprover-community",
-   "rev": "97d68c420815bcbd8abc9915155055423d8775c7",
+   "rev": "d62eab0cc36ea522904895389c301cf8d844fd69",
    "name": "mathlib",
    "manifestFile": "lake-manifest.json",
-   "inputRev": "master",
+   "inputRev": "d62eab0cc36ea522904895389c301cf8d844fd69",
    "inherited": false,
    "configFile": "lakefile.lean"},
   {"url": "https://github.com/leanprover-community/plausible",
    "type": "git",
    "subDir": null,
    "scope": "leanprover-community",
-   "rev": "8864a73bf79aad549e34eff972c606343935106d",
+   "rev": "304c5e2f490d546134c06bf8919e13b175272084",
    "name": "plausible",
    "manifestFile": "lake-manifest.json",
    "inputRev": "main",
@@ -25,7 +25,7 @@
    "type": "git",
    "subDir": null,
    "scope": "leanprover-community",
-   "rev": "2ed4ba69b6127de8f5c2af83cccacd3c988b06bf",
+   "rev": "25078369972d295301f5a1e53c3e5850cf6d9d4c",
    "name": "LeanSearchClient",
    "manifestFile": "lake-manifest.json",
    "inputRev": "main",
@@ -35,7 +35,7 @@
    "type": "git",
    "subDir": null,
    "scope": "leanprover-community",
-   "rev": "451499ea6e97cee4c8979b507a9af5581a849161",
+   "rev": "f5e58ef1f58fc0cbd92296d18951f45216309e48",
    "name": "importGraph",
    "manifestFile": "lake-manifest.json",
    "inputRev": "main",
@@ -45,17 +45,17 @@
    "type": "git",
    "subDir": null,
    "scope": "leanprover-community",
-   "rev": "fb8ed0a85a96e3176f6e94b20d413ea72d92576d",
+   "rev": "632ca63a94f47dbd5694cac3fd991354b82b8f7a",
    "name": "proofwidgets",
    "manifestFile": "lake-manifest.json",
-   "inputRev": "v0.0.77",
+   "inputRev": "v0.0.59",
    "inherited": true,
    "configFile": "lakefile.lean"},
   {"url": "https://github.com/leanprover-community/aesop",
    "type": "git",
    "subDir": null,
    "scope": "leanprover-community",
-   "rev": "1fa48c6a63b4c4cda28be61e1037192776e77ac0",
+   "rev": "9264d548cf1ccf0ba454b82f931f44c37c299fc1",
    "name": "aesop",
    "manifestFile": "lake-manifest.json",
    "inputRev": "master",
@@ -65,7 +65,7 @@
    "type": "git",
    "subDir": null,
    "scope": "leanprover-community",
-   "rev": "95c2f8afe09d9e49d3cacca667261da04f7f93f7",
+   "rev": "36ce5e17d6ab3c881e0cb1bb727982507e708130",
    "name": "Qq",
    "manifestFile": "lake-manifest.json",
    "inputRev": "master",
@@ -75,7 +75,7 @@
    "type": "git",
    "subDir": null,
    "scope": "leanprover-community",
-   "rev": "c44068fa1b40041e6df42bd67639b690eb2764ca",
+   "rev": "78e1181c4752c7e10874d2ed5a6a15063f4a35b6",
    "name": "batteries",
    "manifestFile": "lake-manifest.json",
    "inputRev": "main",
@@ -85,10 +85,10 @@
    "type": "git",
    "subDir": null,
    "scope": "leanprover",
-   "rev": "72ae7004d9f0ddb422aec5378204fdd7828c5672",
+   "rev": "4f22c09e7ded721e6ecd3cf59221c4647ca49664",
    "name": "Cli",
    "manifestFile": "lake-manifest.json",
-   "inputRev": "v4.25.0-rc2",
+   "inputRev": "main",
    "inherited": true,
    "configFile": "lakefile.toml"}],
  "name": "aristotle",
diff --git a/lakefile.toml b/lakefile.toml
index 6ff3d89..78641bb 100644
--- a/lakefile.toml
+++ b/lakefile.toml
@@ -12,6 +12,7 @@ maxSynthPendingDepth = 3
 [[require]]
 name = "mathlib"
 scope = "leanprover-community"
+rev = "d62eab0cc36ea522904895389c301cf8d844fd69"
 
 [[lean_lib]]
 name = "Aristotle"
diff --git a/lean-toolchain b/lean-toolchain
index 9407130..cc6fba8 100644
--- a/lean-toolchain
+++ b/lean-toolchain
@@ -1 +1 @@
-leanprover/lean4:v4.25.0-rc2
+leanprover/lean4:v4.20.0-rc5
\ No newline at end of file
diff --git a/run_aristotle.py b/run_aristotle.py
new file mode 100755
index 0000000..68e5d42
--- /dev/null
+++ b/run_aristotle.py
@@ -0,0 +1,9 @@
+import asyncio
+import aristotlelib
+
+async def main():
+    # Prove a theorem from a Lean file
+    solution_path = await aristotlelib.Project.prove_from_file("/home/kebekus/Mathe/aristotle/Basic.lean")
+    print(f"Solution saved to: {solution_path}")
+
+asyncio.run(main())