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EP0127815A2
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EP
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Data compression method
Assignee: International Business Machines Corp
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Filing: 1984-05-16
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Granted: —
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Expires: 2004-05-16
Abstract
Abstract Communications between a Host Computing System and a number of remote terminals is enhanced by a data compression method which modifies the data compression method of Lempel and Ziv by the addition of new character and new string extensions to improve the compression ratio, and a least recently used routine to limit the encoding tables to a fixed size to significantly improve data transmission efficiency.
Inventors
- 👤 Victor Saul Miller
- 👤 Mark N. Wegman
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-05 23:16
CPC Classifications
H; H03; H03M; H03M7/00; H03M7/30; H03M7/3084; H03M7/3088; G; G06; G06T; G06T9/00; G06T9/005
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
62 words
A method for data compression of individual sequences in a data stream, comprising the steps of: initializing a set of strings to consist of n sequences; determining a longest string S of the set which matches a current string; generating an identifier I for S; transmitting I to a utilization device; decoding I at said utilization device to recover said string S.
Claim 2
Independent Claim
62 words
A method for data compression of individual sequences in a data stream, comprising the steps of: initializing a set of strings to consist of n sequences; determining a longest string S of the set which matches a current string; generating an identifier I for S; transmitting I to a utilization device; decoding I at said utilization device to recover said string S.
Claim 3
Dependent Claim
69 words
A method according to claim 1, further comprising the step of: adding a new string S' to said set where S' comprises a concatenation of a previous string match and said current string match; assigning an identifier k to string S'; advancing an input position to a next character in said stream; outouting an identifier m to indicate a match; and repeating the above steps for a next string.
Claim 4
Independent Claim
59 words
A method for data compression of individual sequences in a data stream, comprising the steps of: initializing a set of strings to consist of n sequences; determining a longest string S of the set which matches a current string; testing a dictionary in storage containing said set of strings for an empty slot to store a new matched string.
Claim 5
Independent Claim
59 words
A method for data compression of individual sequences in a data stream, comprising the steps of: initializing a set of strings to consist of n sequences; determining a longest string S of the set which matches a current string; testing a dictionary in storage containing said set of strings for an empty slot to store a new matched string.
Claim 6
Dependent Claim
51 words
A method according to claim 3, further comprising the steps of: deleting a least recently used string from said dictionary if no empty slot is found to create an empty slot; assigning a slot identifier j to said empty slot found or created from the above steps of testing and deleting.
Claim 7
Independent Claim
161 words
A method for data compression of individual sequences in a data stream, comprising the steps of: initializing a set of strings to consist of n sequences; determining a longest string S of the set which matches a current string; generating an identifier I for S; transmitting I to a utilization device; testing a dictionary in storage containing said set of strings for an empty slot; deleting least recently used string from said dictionary if no empty slot is found to create an empty slot; assigning slot identifier j to said empty slot found or created from the above steps of testing and deleting; adding a new string S' to said set where S' comprises a concatenation of a previous string match and said current string match; assigning an identifier k to string S'; advancing the input position to a next character in said stream; outputting an identifier m to indicate a match; and repeating the above steps for a next string.
Claim 8
Independent Claim
161 words
A method for data compression of individual sequences in a data stream, comprising the steps of: initializing a set of strings to consist of n sequences; determining a longest string S of the set which matches a current string; generating an identifier I for S; transmitting I to a utilization device; testing a dictionary in storage containing said set of strings for an empty slot; deleting least recently used string from said dictionary if no empty slot is found to create an empty slot; assigning slot identifier j to said empty slot found or created from the above steps of testing and deleting; adding a new string S' to said set where S' comprises a concatenation of a previous string match and said current string match; assigning an identifier k to string S'; advancing the input position to a next character in said stream; outputting an identifier m to indicate a match; and repeating the above steps for a next string.
References Cited (Backward Citations)
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