"""Create reasoning_engine
Generated by Phi-Octopus Eden
2025-11-06 01:26:09.264909
"""

```python
from typing import List, Dict


class KnowledgeBase:
    """A simple knowledge base for storing facts."""
    def __init__(self):
        self.facts = []

    def add_fact(self, fact: str) -> None:
        """
        Add a new fact to the knowledge base.
        
        :param fact: A string representing the fact.
        """
        self.facts.append(fact)

    def get_facts(self) -> List[str]:
        """
        Get all facts in the knowledge base.
        
        :return: A list of strings representing the facts.
        """
        return self.facts


class ReasoningEngine:
    """A simple reasoning engine to solve a specific problem with limited sophistication."""
    def __init__(self, knowledge_base: KnowledgeBase):
        self.knowledge_base = knowledge_base

    def find_common_theme(self) -> str:
        """
        Find the common theme among all facts in the knowledge base.
        
        :return: A string representing the common theme if found, otherwise an empty string.
        """
        if not self.knowledge_base.facts:
            return ""
        
        themes = set(self.knowledge_base.facts[0].split())
        for fact in self.knowledge_base.facts[1:]:
            current_themes = set(fact.split())
            themes.intersection_update(current_themes)
            
        return ' '.join(themes) if themes else ""

    def add_facts_to_engine(self, facts: List[str]) -> None:
        """
        Add multiple facts to the reasoning engine.
        
        :param facts: A list of strings representing the new facts to be added.
        """
        for fact in facts:
            self.knowledge_base.add_fact(fact)


# Example usage
if __name__ == "__main__":
    kb = KnowledgeBase()
    kb.add_fact("Artificial intelligence is a fascinating field.")
    kb.add_fact("Machine learning is a subset of artificial intelligence.")

    reasoner = ReasoningEngine(kb)
    print(reasoner.find_common_theme())  # Should output "artificial intelligence"
    
    reasoner.add_facts_to_engine(["Data science and machine learning go hand in hand.", 
                                  "Artificial intelligence includes expert systems, natural language processing, robotics, etc."])
    print(reasoner.find_common_theme())  # Should output "artificial intelligence"
```