turing machine

the engine is chatgpt

but the machine is ME

Signed-off-by: Luong Duc Anh <[email protected]>

first_proj.py

@@ -0,0 +1,115 @@
+# Improved TuringMachine class with debug output and updated transition table per your fix.
+from dataclasses import dataclass
+from typing import Dict, Tuple, List, TypeAlias, Literal
+
+# === Type Aliases ===
+State: TypeAlias = str
+Symbol: TypeAlias = str
+Direction: TypeAlias = Literal["L", "R"]  # precise directions only
+
+TransitionKey: TypeAlias = Tuple[State, Symbol]
+TransitionValue: TypeAlias = Tuple[State, Symbol, Direction]
+TransitionFunction: TypeAlias = Dict[TransitionKey, TransitionValue]
+Tape: TypeAlias = List[Symbol]
+
+
+@dataclass
+class TuringMachine:
+    transition_function: TransitionFunction
+    start_state: State
+    accept_state: State
+    reject_state: State
+    blank_symbol: Symbol = " "
+
+    def run(
+        self, tape_input: str, max_steps: int = 10_000, verbose: bool = True
+    ) -> Tuple[State, Tape]:
+        tape: Tape = list(tape_input) + [self.blank_symbol] * 20
+        head = 0
+        state = self.start_state
+        steps = 0
+
+        def debug_print():
+            tape_view = "".join(tape).replace(self.blank_symbol, "_")
+            head_marker = " " * head + "^"
+            print(
+                f"[{steps:04}] State: {state} | Head: {head} | Tape:\n{tape_view}\n{head_marker}"
+            )
+
+        debug_print()
+        while (
+            state != self.accept_state
+            and state != self.reject_state
+            and steps < max_steps
+        ):
+            if verbose:
+                debug_print()
+            read = tape[head]
+            key = (state, read)
+            if key not in self.transition_function:
+                print(f"No transition for ({state}, '{read}') — rejecting.")
+                state = self.reject_state
+                break
+
+            next_state, write, move = self.transition_function[key]
+            tape[head] = write
+            head += 1 if move == "R" else -1
+            if head < 0:
+                tape.insert(0, self.blank_symbol)
+                head = 0
+            state = next_state
+            steps += 1
+
+        debug_print()
+        return state, tape
+
+
+# Updated transitions
+transitions_cleaned: TransitionFunction = {}
+
+# Scan phase: 1 → X, 0 → Y
+transitions_cleaned[("scan", "1")] = ("scan", "X", "R")
+transitions_cleaned[("scan", "0")] = ("scan", "Y", "R")
+
+transitions_cleaned[("scan", " ")] = ("back", " ", "L")
+
+# Back phase: move left over 0/1/X/Y and turn forward on ' ', 'M', 'N'
+for sym in ["0", "1", "X", "Y"]:
+    transitions_cleaned[("back", sym)] = ("back", sym, "L")
+transitions_cleaned[("back", " ")] = ("forward", " ", "R")
+transitions_cleaned[("back", "M")] = ("forward", "M", "R")
+transitions_cleaned[("back", "N")] = ("forward", "N", "R")
+
+# Forward: if blank, done; if digit → sweep; if mark → prepare copy
+transitions_cleaned[("forward", " ")] = ("accept", " ", "R")
+transitions_cleaned[("forward", "0")] = ("sweep", "0", "L")
+transitions_cleaned[("forward", "1")] = ("sweep", "1", "L")
+transitions_cleaned[("forward", "X")] = ("fw1", "M", "R")  # 1 → M
+transitions_cleaned[("forward", "Y")] = ("fw0", "N", "R")  # 0 → N
+
+# Copy phases
+for sym in ["0", "1", "X", "Y"]:  # ts wont ever meet M N
+    transitions_cleaned[("fw1", sym)] = ("fw1", sym, "R")
+    transitions_cleaned[("fw0", sym)] = ("fw0", sym, "R")
+transitions_cleaned[("fw1", " ")] = ("back", "1", "L")
+transitions_cleaned[("fw0", " ")] = ("back", "0", "L")
+
+# Sweep phase: M → 1, N → 0
+transitions_cleaned[("sweep", "M")] = ("sweep", "1", "L")
+transitions_cleaned[("sweep", "N")] = ("sweep", "0", "L")
+transitions_cleaned[("sweep", "0")] = ("sweep", "0", "L")
+transitions_cleaned[("sweep", "1")] = ("sweep", "1", "L")
+transitions_cleaned[("sweep", " ")] = ("accept", " ", "R")
+
+# Build and run the machine with debug output
+tm = TuringMachine(
+    transition_function=transitions_cleaned,
+    start_state="scan",
+    accept_state="accept",
+    reject_state="reject",
+)
+
+final_state, final_tape = tm.run("00110")
+print("Final State:", final_state)
+print("Final Tape:", "".join(final_tape).strip())
+