Eulerian trails and circuits
Graph theory · Mathematics
Study notes
Q: The square ABCD with diagonal AC: does it have an Eulerian circuit? Trail? Degrees: A=3, B=2, C=3, D=2. Odd vertices: A, C (2 odds). No Eulerian CIRCUIT (needs 0 odds). Eulerian TRAIL exists: start at A, end at C! Try: A-B-C-D-A-C - uses all 5 edges exactly once ✓!