diff --git a/graph_n.py b/graph_n.py
new file mode 100644
index 0000000..381f7a4
--- /dev/null
+++ b/graph_n.py
@@ -0,0 +1,149 @@
+import queue
+import threading
+from enum import Enum
+from typing import override
+
+import simpy
+import simpy.rt
+from prompt_toolkit import PromptSession
+from prompt_toolkit.patch_stdout import patch_stdout
+
+nodes_n = {
+    ("A", "1", "A'"),
+    ("B", "1", "B'"),
+    ("AB", "A", "AB'"),
+    ("A'B", "A'", "A'B'"),
+    ("A'B", "B", "AB"),
+    ("A'B'", "B'", "AB'"),
+}
+
+
+f = {
+    "000": "000",
+    "001": "0NN",
+    "00N": "000",
+    "010": "NNN",
+    "011": "011",
+    "01N": "011",
+    "0N0": "000",
+    "0N1": "011",
+    "0NN": "0NN",
+    "100": "NN0",
+    "101": "NNN",
+    "10N": "NNN",
+    "110": "110",
+    "111": "111",
+    "11N": "11N",
+    "1N0": "110",
+    "1N1": "111",
+    "1NN": "11N",
+    "N00": "000",
+    "N01": "NNN",
+    "N0N": "000",
+    "N10": "110",
+    "N11": "N11",
+    "N1N": "N1N",
+    "NN0": "NN0",
+    "NN1": "NN1",
+    "NNN": "NNN",
+}
+
+
+class Tern(Enum):
+    N = -1
+    U = 0
+    Y = 1
+
+    @override
+    def __str__(self):
+        if self.value == -1:
+            return "0"
+        if self.value == 1:
+            return "1"
+        return "N"
+
+    @classmethod
+    def from_string(cls, s: str) -> "Tern":
+        if s == "N":
+            return Tern.U
+        if s == "0":
+            return Tern.N
+        if s == "1":
+            return Tern.Y
+        return cls[s]
+
+
+def node(env: simpy.Environment, node: tuple[str, str, str], values: dict[str, Tern]):
+    while True:
+        nn, uu, yy = node
+        old = "".join(str(values[x]) for x in node)
+        new = f[old]
+
+        n, u, y = new
+
+        values[nn], values[uu], values[yy] = (
+            Tern.from_string(n),
+            Tern.from_string(u),
+            Tern.from_string(y),
+        )
+        print(values)
+        yield env.timeout(1)
+
+
+def input_thread(commands: queue.Queue[tuple[str, Tern]]):
+    session: PromptSession[str] = PromptSession("> ")
+
+    with patch_stdout():
+        while True:
+            line = session.prompt().strip()
+
+            if line in {"q", "quit", "exit"}:
+                commands.put(("__quit__", Tern.U))
+                break
+
+            try:
+                name, value = line.split()
+                commands.put((name, Tern.from_string(value)))
+            except Exception:
+                print("format: A 1 | A 0 | A N | quit")
+
+
+def user_input_process(
+    env: simpy.Environment,
+    values: dict[str, Tern],
+    commands: queue.Queue[tuple[str, Tern]],
+):
+    while True:
+        while not commands.empty():
+            name, value = commands.get_nowait()
+
+            if name == "__quit__":
+                return
+
+            if name not in values:
+                print(f"unknown node: {name}")
+                continue
+
+            values[name] = value
+            print(f"[t={env.now}] user set {name} = {value}")
+
+        yield env.timeout(0.1)
+
+
+ls = {x: Tern.U for triple in nodes_n for x in triple}
+commands: queue.Queue[tuple[str, Tern]] = queue.Queue()
+
+env = simpy.rt.RealtimeEnvironment(factor=1.0, strict=False)
+
+threading.Thread(
+    target=input_thread,
+    args=(commands,),
+    daemon=True,
+).start()
+
+for n in nodes_n:
+    _ = env.process(node(env, n, ls))
+
+_ = env.process(user_input_process(env, ls, commands))
+
+_ = env.run(until=100)
diff --git a/shell.nix b/shell.nix
new file mode 100644
index 0000000..95591a5
--- /dev/null
+++ b/shell.nix
@@ -0,0 +1,14 @@
+{ pkgs ? import <nixpkgs> {} }:
+
+pkgs.mkShell {
+  packages = [
+    (pkgs.python3.withPackages (pythonPackages: [
+      pythonPackages.simpy
+      pythonPackages.prompt-toolkit
+    ]))
+
+    pkgs.basedpyright
+    pkgs.codex-acp
+    pkgs.clang
+  ];
+}
diff --git a/untitled.c b/untitled.c
new file mode 100644
index 0000000..da3b313
--- /dev/null
+++ b/untitled.c
@@ -0,0 +1,42 @@
+#include <stdio.h>
+
+int counter = 0;
+
+void rec (char *str) {
+    for (size_t i = 0; str[i] != 0; ++i) {
+        if (str[i] == '0') {
+            int t = ++counter;
+            printf("    \"%s\" -> T%d [color=black]\n", str, t);
+            str[i] = '+';
+            printf("    T%d -> \"%s\" [color=green]\n", t, str);
+            rec(str);
+            str[i] = '-';
+            printf("    T%d -> \"%s\" [color=red]\n", t, str);
+            rec(str);
+            str[i] = '0';
+        }
+    }
+}
+
+int main2() {
+    char str[] = "0000\0";
+    printf("digraph {\n");
+    rec(str);
+    printf("    ");
+    if (counter > 1) {
+        printf("T1");
+    }
+    for (int i = 2; i <= counter; ++i) {
+        printf(", T%d", i);
+    }
+    if (counter > 1) {
+        printf(" [shape=point]");
+    }
+    printf("\n}\n");
+}
+
+int main(void) {
+    unsigned short int x = 65535; // 1111 1111 1111 1111
+    short int y = x;
+    printf("%d", y);
+}