concept d - ary heap in category algorithms

This is an excerpt from Manning's book Algorithms and Data Structures in Action MEAP V14. Login to get full access to this book.

Next, in section 2.4 we describe the priority queue API[1], and we show with an example how to use it, as a black box, before delving into its internals in sections 2.5 and 2.6. In the former we analyze in detail how a d-ary heap works, describing the functioning of its methods. In section 2.6 we delve into the implementation of a d-way heap.

Figure 2.17 The result of the next couple of steps in the Huffman coding algorithm:
(A) We dequeue and merge the top two nodes on the heap, C and D. At the end of this step, EF and CD becomes the two smallest nodes in the heap.
(B) Now we merge those two nodes into CDEF, and we add it back to the heap. Which node between CDEF and B will be kept at the top of the priority queue is an implementation detail, and it’s irrelevant for the Huffman coding algorithm (the code will change slightly depending on which one is extracted first, but it’s compression ratio will remain unchanged).
The next steps are easy to figure, also using figure 2.15 as a reference.