------
## 最终结论
```python
def isSelfCrossing(x):
    n = len(x)
    if n < 4:
        return False

    for i in range(3, n):
        # Fourth line crosses first line and onward
        if x[i] >= x[i-2] and x[i-1] <= x[i-3]:
            return True
        # Fifth line meets first line and onward
        if i >= 4 and x[i-1] == x[i-3] and x[i] + x[i-4] >= x[i-2]:
            return True
        # Sixth line crosses first line and onward
        if i >= 5 and x[i-2] >= x[i-4] and x[i] + x[i-4] >= x[i-2] and x[i-1] <= x[i-3] and x[i-1] + x[i-5] >= x[i-3]:
            return True

    return False
```