title: Online and offline heuristics for inferring hierarchies of repetitions in sequences

authors: Nevill-Manning, Craig G.

subjects: dictionary compression

abstract: Hierarchical dictionary-based compression schemes form a grammar for a text by replacing each repeated string with a production rule. While such schemes usually operate online, making a replacement as soon as repetition is detected, offline operation permits greater freedom in choosing the order of replacement. In this paper, we compare the online method with three offline heuristics for selecting the next substring to replace: longest string first, most common string first, and the string that minimized the size of the grammar locally. Surprisingly, two of the offline techniques, like the online method, run in time linear in the size of the input. We evaluate each technique on artificial and natural sequences. In general, the locally-most-compressive heuristic performs best, followed by most frequent, the online technique, and, lagging by some distance, the longest-first technique.

text: Online and offline heuristics for inferring hierarchies of repetitions in sequences Hierarchical dictionary-based compression schemes form a grammar for a text by replacing each repeated string with a production rule. While such schemes usually operate online, making a replacement as soon as repetition is detected, offline operation permits greater freedom in choosing the order of replacement. In this paper, we compare the online method with three offline heuristics for selecting the next substring to replace: longest string first, most common string first, and the string that minimized the size of the grammar locally. Surprisingly, two of the offline techniques, like the online method, run in time linear in the size of the input. We evaluate each technique on artificial and natural sequences. In general, the locally-most-compressive heuristic performs best, followed by most frequent, the online technique, and, lagging by some distance, the longest-first technique.

year: 2000

title: Balanced cross-section and crustal shortening analysis in the Tanggula-Tuotuohe Area, Northern Tibet

authors: Li, Yalin

subjects: Tibetan plateau

abstract: The Tanggula (唐古拉) thrust system and the Tuotuohe (沱沱河) foreland basin, which represent major Cenozoic tectonic units of the central Tibetan plateau, have been recently studied. Field investigation, analyses of deformation and construction of two restored balanced structural sections suggest 75–100 km (51%–64%) of N-S shortening in the Tanggula thrust system and 55–114 km (42%–47%) of N-S shortening in the Tuotuohe basin. The shortening ratios indicate that the Tanggula-Tuotuohe area has undergone intensive deformation and crustal shortening during the Early Tertiary, resulting not only in crustal thickening, but also in large scale volcanism and in rapid uplift of the Tanggula Mountains.

text: Balanced cross-section and crustal shortening analysis in the Tanggula-Tuotuohe Area, Northern Tibet The Tanggula (唐古拉) thrust system and the Tuotuohe (沱沱河) foreland basin, which represent major Cenozoic tectonic units of the central Tibetan plateau, have been recently studied. Field investigation, analyses of deformation and construction of two restored balanced structural sections suggest 75–100 km (51%–64%) of N-S shortening in the Tanggula thrust system and 55–114 km (42%–47%) of N-S shortening in the Tuotuohe basin. The shortening ratios indicate that the Tanggula-Tuotuohe area has undergone intensive deformation and crustal shortening during the Early Tertiary, resulting not only in crustal thickening, but also in large scale volcanism and in rapid uplift of the Tanggula Mountains.

year: 2011

title: Te rima tekau ngahurutanga o Te Whare Wānanga o Waikato

authors: Dixon, Ngahuia

subjects: Tohu mātauranga

abstract: E te Whare Wānanga o Waikato – te tohu o te mātauranga, tēnā koe.  Tēnā koe i roto i tō rima tekau tau ngahurutanga.  Kua pakeke haere koe.  Kua tau atu koe ki tērā kaumātuatanga nō reira me mihi ka tika.  He hōnore nui tēnei mōu ake i te mea nāu te moana o mātauranga i roto o Waikato i tuku kia rere, kia pari, ka rere anō.  He wai marino ēnei i ētehi wā, he rehutai i ētehi atu,  he wā anō ka karekare, ka haruru rānei i te pai o te rere o āu mahi.  Ahakoa ēnei huringa o ngā awa o te wā, kei te rere tonu te moana nei, me ōna pikonga ki uru, ki rāwhiti, ki tonga, ki raki rānei, arā ki ngā pito katoa o te ao.  He mātauranga ēnei i tukuna e koe kia pīoioi i te ao.  Hei aha - hei whakawhānui ki te mātatoru o te tangata, he aha kei ō whare kōrero, hei whakakīkī haere i ā rātou kete mātauranga, ahakoa Māori, tauiwi huri noa.  Koinei ngā korowai mō ngā manu i kai i te mātauranga nāu i rumaki.   Ināianei arā te kōrero:

Nō rātou, nō mātou, nō tātou te ao 

E kore e mimiti ēnei huarahi tautoko āu, - nā mēnā ka tūwhera tonu tō ngākau ki ngā kete kōrero, mātauranga āku ake a ngāi-Māori, kei hea mai tō mana.

text: Te rima tekau ngahurutanga o Te Whare Wānanga o Waikato E te Whare Wānanga o Waikato – te tohu o te mātauranga, tēnā koe.  Tēnā koe i roto i tō rima tekau tau ngahurutanga.  Kua pakeke haere koe.  Kua tau atu koe ki tērā kaumātuatanga nō reira me mihi ka tika.  He hōnore nui tēnei mōu ake i te mea nāu te moana o mātauranga i roto o Waikato i tuku kia rere, kia pari, ka rere anō.  He wai marino ēnei i ētehi wā, he rehutai i ētehi atu,  he wā anō ka karekare, ka haruru rānei i te pai o te rere o āu mahi.  Ahakoa ēnei huringa o ngā awa o te wā, kei te rere tonu te moana nei, me ōna pikonga ki uru, ki rāwhiti, ki tonga, ki raki rānei, arā ki ngā pito katoa o te ao.  He mātauranga ēnei i tukuna e koe kia pīoioi i te ao.  Hei aha - hei whakawhānui ki te mātatoru o te tangata, he aha kei ō whare kōrero, hei whakakīkī haere i ā rātou kete mātauranga, ahakoa Māori, tauiwi huri noa.  Koinei ngā korowai mō ngā manu i kai i te mātauranga nāu i rumaki.   Ināianei arā te kōrero:

Nō rātou, nō mātou, nō tātou te ao 

E kore e mimiti ēnei huarahi tautoko āu, - nā mēnā ka tūwhera tonu tō ngākau ki ngā kete kōrero, mātauranga āku ake a ngāi-Māori, kei hea mai tō mana.

year: 2016