Data Mining Lecture 5: PrefixSpan Algorithm

What is the function of the PrefixSpan algorithm?

To find the frequent events and generate projected databases (correct)
To process the data in a breadth-first manner
To focus on suffixes rather than prefixes
To store a detailed version of the database

What do suffixes represent in the context of sequences?

The set of events at the beginning of a sequence
The occurrence of the last event in the prefix at the same time as the first event in the suffix
The first event in the sequence
The rest of the elements in the sequence after the prefix (correct)

What does the notation (_) indicate in the context of prefixes and suffixes?

It signifies the end of a sequence
It shows the time relationship between the last event in the prefix and the first event in the suffix (correct)
It indicates an error in the sequence
It represents a prefix

How does PrefixSpan algorithm store a compact version of the database?

By using a projected database for each frequent event (B) Signup and view all the answers

What is considered in the projected database generated by PrefixSpan algorithm for each frequent event?

The earliest occurrence of the event (A) Signup and view all the answers

In what manner does PrefixSpan algorithm process the data?

In a depth-first manner (B) Signup and view all the answers

What is the main issue with processing data streams?

Challenges in storing the whole data stream in memory (B) Signup and view all the answers

What is the purpose of generating the projected databases for frequent events?

To find the sequences with common prefixes (B) Signup and view all the answers

Why is it not possible to perform multiple passes over data streams?

Increasing volume and velocity of the data (C) Signup and view all the answers

What is a characteristic of stream mining algorithms?

They need to be re-designed for one pass over the data (D) Signup and view all the answers

What does the term 'projected database' refer to in this context?

A database with sequences found frequent from a specific event (B) Signup and view all the answers

Why do stream mining algorithms face memory limits?

Due to the finite storage space and need to process in batches (D) Signup and view all the answers

What is a key issue with processing data streams in real-time?

The requirement for fast and efficient processing (B) Signup and view all the answers

Why is it necessary to re-design stream mining algorithms?

To address constraints on multiple passes over the data (B) Signup and view all the answers

What is meant by 'frequent events' in the context of stream data processing?

Events that occur often in the data stream (A) Signup and view all the answers

What is one of the issues related to memory limits when processing stream data?

The trade-off between accuracy and storage space (C) Signup and view all the answers

What is the key similarity between the PrefixSpan algorithm and the FP-Growth algorithm?

Both algorithms store a compact version of the database (C) Signup and view all the answers

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 (A) Signup and view all the answers

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 (D) Signup and view all the answers

Why does PrefixSpan algorithm generate a list of sequences having a certain event as a prefix?

To aid in further data processing (A) Signup and view all the answers

What is assumed about the order of events within an element in the context of prefixes and suffixes?

They occur in alphabetical order (A) Signup and view all the answers

What does a prefix represent in relation to a sequence?

The set of events at the beginning of a sequence (B) Signup and view all the answers

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 (B) Signup and view all the answers

What is the primary reason for the re-design of stream mining algorithms?

The increasing volume and velocity of data (A) Signup and view all the answers

In the context of stream data processing, what does the term 'projected database' refer to?

A reduced-size database generated for each frequent event (B) Signup and view all the answers

What characteristic is typical of stream mining algorithms?

Requirement for re-design due to volume and velocity of data (A) Signup and view all the answers

Why is it not feasible to perform multiple passes over data streams?

Due to memory limitations (C) Signup and view all the answers

What is considered in the projected database generated by PrefixSpan algorithm for each frequent event?

Reduced-size databases for each frequent event (C) Signup and view all the answers

'Frequent events' in the context of stream data processing refer to events that:

Occur multiple times in the entire data stream (A) Signup and view all the answers

What is one of the key issues with processing data streams in real-time?

The inability to store the entire data stream in memory (A) Signup and view all the answers

What does 'frequent' indicate in the context of stream data processing?

Events that occur multiple times in the entire data stream (D) Signup and view all the answers

What is meant by 'suffixes' in the context of sequences?

Events that occur at the end of a sequence database (D) Signup and view all the answers

Data Mining Lecture 5: PrefixSpan Algorithm

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Questions and Answers

What is the function of the PrefixSpan algorithm?

What do suffixes represent in the context of sequences?

What does the notation (_) indicate in the context of prefixes and suffixes?

How does PrefixSpan algorithm store a compact version of the database?

What is considered in the projected database generated by PrefixSpan algorithm for each frequent event?

In what manner does PrefixSpan algorithm process the data?

What is the main issue with processing data streams?

What is the purpose of generating the projected databases for frequent events?

Why is it not possible to perform multiple passes over data streams?

What is a characteristic of stream mining algorithms?

What does the term 'projected database' refer to in this context?

Why do stream mining algorithms face memory limits?

What is a key issue with processing data streams in real-time?

Why is it necessary to re-design stream mining algorithms?

What is meant by 'frequent events' in the context of stream data processing?

What is one of the issues related to memory limits when processing stream data?

What is the key similarity between the PrefixSpan algorithm and the FP-Growth algorithm?

What is the primary purpose of generating the projected database for each frequent event in the PrefixSpan algorithm?

What does the notation (_) indicate in the context of prefixes and suffixes?

Why does PrefixSpan algorithm generate a list of sequences having a certain event as a prefix?

What is assumed about the order of events within an element in the context of prefixes and suffixes?

What does a prefix represent in relation to a sequence?

In the context of stream data processing, what is the main challenge related to memory limits?

What is the primary reason for the re-design of stream mining algorithms?

In the context of stream data processing, what does the term 'projected database' refer to?

What characteristic is typical of stream mining algorithms?

Why is it not feasible to perform multiple passes over data streams?

What is considered in the projected database generated by PrefixSpan algorithm for each frequent event?

'Frequent events' in the context of stream data processing refer to events that:

What is one of the key issues with processing data streams in real-time?

What does 'frequent' indicate in the context of stream data processing?

What is meant by 'suffixes' in the context of sequences?

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