doubt on index

Question

if  p:order of the internal of b+ tree which represents the maximum number of child pointer that the internal node can have

then the minimum number of keys possible in the internal node is  (ceil(p/2)-1)

doubt: if q:order of the leaf node in the b+ tree which represents the maximum number of (key,value) pointer pairs present in the leaf node then what is the minimum number of keys possible in the leaf node? 

Answer 1

If the order of a leaf node q of a B+ tree is defined as the maximum number of <key,pointer> pairs, then the minimum number of <key,pointer> pairs that can be present in the leaf node is ceil(q/2).

Comments

can you give any justification...

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this is how the constraints are defined for leaf nodes of b+ trees, i. e. Leaf nodes must have at least ceil(n/2) keys and atmost n keys where n is the order of leaf node as per the definition That is used in the question.

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Can you provide the link where you get that expression. ...

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Are you getting  that expression in any standard book?

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Check this out

https://en.wikipedia.org/wiki/B%2B_tree#Overview