32 Questions
What is the function of the PrefixSpan algorithm?
To find the frequent events and generate projected databases
What do suffixes represent in the context of sequences?
The rest of the elements in the sequence after the prefix
What does the notation (_) indicate in the context of prefixes and suffixes?
It shows the time relationship between the last event in the prefix and the first event in the suffix
How does PrefixSpan algorithm store a compact version of the database?
By using a projected database for each frequent event
What is considered in the projected database generated by PrefixSpan algorithm for each frequent event?
The earliest occurrence of the event
In what manner does PrefixSpan algorithm process the data?
In a depth-first manner
What is the main issue with processing data streams?
Challenges in storing the whole data stream in memory
What is the purpose of generating the projected databases for frequent events?
To find the sequences with common prefixes
Why is it not possible to perform multiple passes over data streams?
Increasing volume and velocity of the data
What is a characteristic of stream mining algorithms?
They need to be re-designed for one pass over the data
What does the term 'projected database' refer to in this context?
A database with sequences found frequent from a specific event
Why do stream mining algorithms face memory limits?
Due to the finite storage space and need to process in batches
What is a key issue with processing data streams in real-time?
The requirement for fast and efficient processing
Why is it necessary to re-design stream mining algorithms?
To address constraints on multiple passes over the data
What is meant by 'frequent events' in the context of stream data processing?
Events that occur often in the data stream
What is one of the issues related to memory limits when processing stream data?
The trade-off between accuracy and storage space
What is the key similarity between the PrefixSpan algorithm and the FP-Growth algorithm?
Both algorithms store a compact version of the database
What is the primary purpose of generating the projected database for each frequent event in the PrefixSpan algorithm?
To generate the list of sequences having the event as a prefix
What does the notation (_) indicate in the context of prefixes and suffixes?
That the last event in the prefix occurs at the same time as the first event in the suffix
Why does PrefixSpan algorithm generate a list of sequences having a certain event as a prefix?
To aid in further data processing
What is assumed about the order of events within an element in the context of prefixes and suffixes?
They occur in alphabetical order
What does a prefix represent in relation to a sequence?
The set of events at the beginning of a sequence
In the context of stream data processing, what is the main challenge related to memory limits?
The inability to store the whole data stream in memory
What is the primary reason for the re-design of stream mining algorithms?
The increasing volume and velocity of data
In the context of stream data processing, what does the term 'projected database' refer to?
A reduced-size database generated for each frequent event
What characteristic is typical of stream mining algorithms?
Requirement for re-design due to volume and velocity of data
Why is it not feasible to perform multiple passes over data streams?
Due to memory limitations
What is considered in the projected database generated by PrefixSpan algorithm for each frequent event?
Reduced-size databases for each frequent event
'Frequent events' in the context of stream data processing refer to events that:
Occur multiple times in the entire data stream
What is one of the key issues with processing data streams in real-time?
The inability to store the entire data stream in memory
What does 'frequent' indicate in the context of stream data processing?
Events that occur multiple times in the entire data stream
What is meant by 'suffixes' in the context of sequences?
Events that occur at the end of a sequence database
Learn about the PrefixSpan algorithm, which processes data in a depth-first manner and stores a compact version of the database in the form of a 'projected database'. Understand the concepts of prefixes and suffixes in sequence mining.
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