Update DB-2021.md

Author: heathersherry

topics/DB-2021.md

@@ -10,3 +10,6 @@ Papers of Other Interesting Topics:
 1. Fast Core-based Top-k Frequent Pattern Discovery in Knowledge Graphs
 2. NewsLink: Empowering Intuitive News Search with Knowledge Graphs
 3. Property Graph Schema Optimization for Domain-Specific Knowledge Graphs [[Paper](https://arxiv.org/pdf/2003.11580.pdf)]
+4. Efficient Relation-Aware Scoring Function Search for Knowledge Graph Embedding
+5. SAKE: Spatial Question Answering over Knowledge Graph Based on Embedding Techniques
+6. Influence Maximization Based on Dynamic Personal Perception in Knowledge Graph