The sum over all external (square) nodes of the lengths of the paths from the root of an extended binary tree to each node. For example, in the tree above, the external path length is 25 (Knuth 1997, pp. 399-400). The internal and external path lengths are related by E=I+2n, where n is the number of internal nodes.
Insert a File Path—Wolfram Language Documentation
Huffman Coding -- from Wolfram MathWorld
Chromatic Invariant -- from Wolfram MathWorld
DS: GATE CSE 1991 Question: 01,viii
MultiwayPetriNet Wolfram Function Repository
Wolfram Alpha: The Physicist Turned a Successful Entrepreneur - FourWeekMBA
Wiener process - Wikipedia
Weighted Path length
Path Integral -- from Wolfram MathWorld
Sensors, Free Full-Text
GATE 1991, DS, EXTERNAL PATH LENGTH, BINARY, GATE TEST SERIES, SOLUTIONS ADDA
The Story Continues: Announcing Version 14 of Wolfram Language and Mathematica—Stephen Wolfram Writings
Wolfram Language: Programming Language + Built-In Knowledge
Hamiltonian path - Wikipedia
