BERT wordpiece tokenizer differers from official HF implementation

[cebtenzzre]

Our wordpiece tokenizer has issues with unicode. One of the problems is incomplete NFD normalization, causing many characters with accents to be dropped entirely when tokenized. Examples include Kantō -> Kant and lǜshi -> lshi.

Here is the diff for nomic-embed-text-v1 on wikitext.test.raw:

Diff

--- good_tokens.txt	2024-02-14 14:57:16.501519622 -0500
+++ lcpp_tokens.txt	2024-02-14 14:57:16.832522224 -0500
@@ -3665,8 +3665,8 @@
 1006: (
 100: [UNK]
 1790: 史
-11895: shi
-11895: shi
+14021: sh
+14021: sh
 1007: )
 1012: .
 1996: the
@@ -3848,7 +3848,7 @@
 1006: (
 100: [UNK]
 100: [UNK]
-11895: shi
+14021: sh
 25981: sheng
 1007: )
 1010: ,
@@ -4490,8 +4490,8 @@
 2124: known
 2005: for
 2010: his
-16299: lush
-2072: ##i
+1048: l
+6182: ##shi
 1010: ,
 1037: a
 2828: type
@@ -4538,8 +4538,8 @@
 1012: .
 2010: his
 2190: best
-16299: lush
-2072: ##i
+1048: l
+6182: ##shi
 2224: use
 1996: the
 5903: parallel
@@ -5255,8 +5255,8 @@
 1999: in
 17903: transforming
 1996: the
-16299: lush
-2072: ##i
+1048: l
+6182: ##shi
 2013: from
 8210: mere
 2773: word
@@ -5400,7 +5400,6 @@
 22281: mats
 19098: ##uo
 24234: bash
-2080: ##o
 1010: ,
 1996: the
 2200: very
@@ -5483,10 +5482,9 @@
 2004: as
 25277: bunk
 2050: ##a
-18454: shu
+14021: sh
 2890: ##re
 4509: ##ish
-2226: ##u
 1999: in
 1996: the
 6280: 9th
@@ -5570,11 +5568,11 @@
 18952: sai
 6806: ##ho
 22332: ##kus
-6979: ##hu
+2232: ##h
 1012: .
 2010: his
 3076: student
-14684: chu
+10381: ch
 5289: ##gan
 25540: eng
 8454: ##ets
@@ -5598,14 +5596,14 @@
 18443: preface
 2015: ##s
 1012: .
-14684: chu
+10381: ch
 5289: ##gan
 1005: '
 1055: s
 3076: student
 21025: gi
-3527: ##do
-18454: shu
+2094: ##d
+14021: sh
 17426: ##shin
 2018: had
 2485: close
@@ -5637,7 +5635,7 @@
 2028: one
 2154: day
 9152: ni
-5558: ##jo
+3501: ##j
 10930: yo
 6182: ##shi
 15319: ##moto
@@ -5661,7 +5659,7 @@
 1010: ,
 2356: asked
 21025: gi
-3527: ##do
+2094: ##d
 1010: ,
 1000: "
 2323: should
@@ -5678,7 +5676,7 @@
 1029: ?
 1000: "
 21025: gi
-3527: ##do
+2094: ##d
 15048: dared
 2000: to
 7514: reply
@@ -5772,7 +5770,6 @@
 2386: ##man
 1010: ,
 24234: bash
-2080: ##o
 1010: ,
 1998: and
 18454: shu
@@ -5817,8 +5814,8 @@
 11865: fu
 1005: '
 1055: s
-16299: lush
-2072: ##i
+1048: l
+6182: ##shi
 1006: (
 100: [UNK]
 100: [UNK]
@@ -5847,7 +5844,7 @@
 14483: ##cian
 5784: scholars
 1998: and
-16480: cho
+10381: ch
 11483: ##nin
 1006: (
 27938: townspeople
@@ -5892,12 +5889,12 @@
 4261: 37
 1997: of
 11721: ga
-6806: ##ho
+2232: ##h
 21122: bun
-14235: ##shu
+4095: ##sh
 2008: that
 1062: z
-14428: ##ime
+2213: ##m
 2072: ##i
 1031: [
 4241: du
@@ -5945,7 +5942,6 @@
 22281: mats
 19098: ##uo
 24234: bash
-2080: ##o
 1010: ,
 1996: the
 4602: greatest
@@ -6151,8 +6147,8 @@
 7893: verse
 1010: ,
 2030: or
-16299: lush
-2072: ##i
+1048: l
+6182: ##shi
 1007: )
 1010: ,
 1998: and
@@ -9195,7 +9191,7 @@
 1996: the
 11003: preceding
 11865: fu
-6499: ##so
+2015: ##s
 2465: class
 1010: ,
 2027: they
@@ -9216,7 +9212,6 @@
 1996: the
 2307: great
 26044: kant
-2080: ##o
 8372: earthquake
 1999: in
 4927: 1923
@@ -9490,7 +9485,7 @@
 1997: of
 1996: the
 11865: fu
-6499: ##so
+2015: ##s
 1030: @
 1011: -
 1030: @
@@ -9614,10 +9609,10 @@
 2142: united
 2163: states
 1012: .
-20251: sato
+2938: sat
 8915: te
 10422: ##tsu
-28160: ##taro
+7559: ##tar
 1010: ,
 1037: a
 2887: japanese
@@ -9676,7 +9671,7 @@
 2023: this
 6463: ratio
 1010: ,
-20251: sato
+2938: sat
 14833: theo
 18425: ##rized
 1010: ,
@@ -10020,7 +10015,7 @@
 1997: of
 1996: the
 11865: fu
-6499: ##so
+2015: ##s
 2465: class
 2020: were
 4821: ultimately
@@ -10032,7 +10027,7 @@
 2093: three
 2062: more
 11865: fu
-6499: ##so
+2015: ##s
 1030: @
 1011: -
 1030: @
@@ -10048,7 +10043,7 @@
 1010: ,
 1998: and
 1044: h
-10513: ##yu
+2100: ##y
 3654: ##ga
 1007: )
 2020: were
@@ -10089,7 +10084,7 @@
 2063: ##e
 1998: and
 1044: h
-10513: ##yu
+2100: ##y
 3654: ##ga
 2127: until
 1996: the
@@ -10115,7 +10110,7 @@
 5082: progress
 1997: of
 11865: fu
-6499: ##so
+2015: ##s
 1005: '
 1055: s
 2810: construction
@@ -10145,7 +10140,7 @@
 4757: ##ss
 1996: the
 11865: fu
-6499: ##so
+2015: ##s
 1030: @
 1011: -
 1030: @
@@ -10251,7 +10246,7 @@
 1999: in
 1996: the
 11865: fu
-6499: ##so
+2015: ##s
 2465: class
 1998: and
 3041: earlier
@@ -10442,7 +10437,7 @@
 1999: in
 1996: the
 11865: fu
-6499: ##so
+2015: ##s
 2465: class
 1012: .
 2023: this
@@ -10514,7 +10509,7 @@
 1997: of
 1996: the
 11865: fu
-6499: ##so
+2015: ##s
 2465: class
 2008: that
 2009: it
@@ -10953,7 +10948,7 @@
 1007: )
 1006: (
 1044: h
-10513: ##yu
+2100: ##y
 3654: ##ga
 1998: and
 2003: is
@@ -10969,7 +10964,7 @@
 27829: kam
 26029: ##pon
 20996: ro
-2175: go
+1043: g
 2300: water
 1030: @
 1011: -
@@ -11082,7 +11077,7 @@
 1007: )
 1998: and
 1044: h
-10513: ##yu
+2100: ##y
 3654: ##ga
 14872: exceeded
 2008: that
@@ -11224,7 +11219,7 @@
 2063: ##e
 1998: and
 1044: h
-10513: ##yu
+2100: ##y
 3654: ##ga
 2018: had
 2093: three
@@ -13815,7 +13810,7 @@
 7584: conversion
 2138: because
 1044: h
-10513: ##yu
+2100: ##y
 3654: ##ga
 2018: had
 4265: suffered
@@ -13869,7 +13864,8 @@
 1012: .
 1996: the
 11865: fu
-17063: ##sos
+2015: ##s
+2015: ##s
 2020: were
 5115: scheduled
 2000: to
@@ -15034,7 +15030,7 @@
 4170: fleet
 1012: .
 1044: h
-10513: ##yu
+2100: ##y
 3654: ##ga
 2018: had
 2019: an
@@ -15148,7 +15144,6 @@
 4927: 1923
 2307: great
 26044: kant
-2080: ##o
 8372: earthquake
 4930: struck
 1010: ,
@@ -15206,7 +15201,7 @@
 4739: 1931
 1998: and
 1044: h
-10513: ##yu
+2100: ##y
 3654: ##ga
 1005: '
 1055: s
@@ -15269,7 +15264,7 @@
 2257: august
 4347: 1937
 1044: h
-10513: ##yu
+2100: ##y
 3654: ##ga
 10768: fe
 22155: ##rrie
@@ -15405,8 +15400,8 @@
 1996: the
 2422: light
 6839: carrier
-7570: ho
-22231: ##sho
+1044: h
+4095: ##sh
 2004: as
 6802: distant
 3104: cover
@@ -15431,7 +15426,7 @@
 2063: ##e
 1998: and
 1044: h
-10513: ##yu
+2100: ##y
 3654: ##ga
 4066: sort
 6340: ##ied
@@ -15503,7 +15498,7 @@
 3282: gun
 1997: of
 1044: h
-10513: ##yu
+2100: ##y
 3654: ##ga
 1005: '
 1055: s
@@ -15615,7 +15610,7 @@
 1030: @
 5902: admiral
 11895: shi
-3217: ##ro
+2099: ##r
 27006: tak
 3022: ##as
 2226: ##u
@@ -15732,7 +15727,7 @@
 3826: 1943
 1998: and
 1044: h
-10513: ##yu
+2100: ##y
 3654: ##ga
 2012: at
 21871: sas
@@ -15797,7 +15792,7 @@
 4397: newly
 2949: completed
 1044: h
-10513: ##yu
+2100: ##y
 3654: ##ga
 1996: the
 2206: following
@@ -16025,7 +16020,8 @@
 5902: admiral
 10147: ji
 3736: ##sa
-23670: ##buro
+8569: ##bu
+2099: ##r
 11472: oz
 10830: ##awa
 1998: and
@@ -16304,7 +16300,7 @@
 1016: 2
 1012: .
 1044: h
-10513: ##yu
+2100: ##y
 3654: ##ga
 2001: was
 8217: lightly
@@ -16495,7 +16491,7 @@
 2886: attack
 1012: .
 1044: h
-10513: ##yu
+2100: ##y
 3654: ##ga
 2001: was
 11551: unsuccessfully
@@ -16583,8 +16579,7 @@
 2005: for
 25933: ama
 4328: ##mi
-9808: os
-16369: ##hima
+24772: ##shima
 1012: .
 2043: when
 2027: they
@@ -16598,7 +16593,7 @@
 4015: transferred
 2000: to
 1044: h
-10513: ##yu
+2100: ##y
 3654: ##ga
 1998: and
 27269: hoisted
@@ -16703,7 +16698,7 @@
 27053: indochina
 1998: and
 1044: h
-10513: ##yu
+2100: ##y
 3654: ##ga
 2150: became
 10565: flagship
@@ -16739,7 +16734,6 @@
 1996: the
 2422: light
 10844: cruiser
-1051: o
 7677: ##yo
 3527: ##do
 2006: on
@@ -16870,7 +16864,6 @@
 2020: were
 13127: escorted
 2011: by
-1051: o
 7677: ##yo
 3527: ##do
 1998: and
@@ -16984,7 +16977,7 @@
 5388: 58
 1998: and
 1044: h
-10513: ##yu
+2100: ##y
 3654: ##ga
 2001: was
 2718: hit
@@ -17126,7 +17119,7 @@
 14107: pumping
 1012: .
 1044: h
-10513: ##yu
+2100: ##y
 3654: ##ga
 2001: was
 1037: a
@@ -43604,7 +43597,6 @@
 1996: the
 2887: japanese
 4290: kong
-2080: ##o
 1998: and
 7632: hi
 7416: ##ei
@@ -47216,7 +47208,7 @@
 3212: navy
 1012: .
 1996: the
-12849: ko
+1047: k
 22513: ##tet
 6342: ##su
 1006: (
@@ -53282,7 +53274,6 @@
 2013: from
 3306: greek
 1174: τ
-29723: ##ε
 29728: ##μ
 16177: ##ν
 29723: ##ε
@@ -53302,7 +53293,6 @@
 1998: and
 1173: σ
 29731: ##π
-29730: ##ο
 16177: ##ν
 29722: ##δ
 29735: ##υ
@@ -100436,7 +100426,6 @@
 1999: in
 1007: )
 1999: in
-1051: o
 6590: ##ita
 7498: prefecture
 1010: ,
@@ -101378,7 +101367,8 @@
 2001: was
 5409: worst
 1999: in
-27603: kochi
+1047: k
+5428: ##chi
 1998: and
 2000: to
 24917: ##kushima
@@ -101796,7 +101786,7 @@
 19808: mina
 4328: ##mi
 21351: ##dai
-3406: ##to
+2102: ##t
 1010: ,
 15052: okinawa
 1012: .
@@ -103992,9 +103982,9 @@
 2345: final
 21042: landfall
 2379: near
-11503: cam
+1039: c
+2213: ##m
 6887: ph
-2050: ##a
 1010: ,
 5148: vietnam
 2006: on
@@ -105809,8 +105799,7 @@
 1998: and
 25933: ama
 4328: ##mi
-9808: os
-16369: ##hima
+24772: ##shima
 2006: on
 2244: september
 2539: 19
@@ -105976,7 +105965,7 @@
 1997: of
 5292: ha
 5428: ##chi
-5558: ##jo
+3501: ##j
 1030: @
 1011: -
 1030: @
@@ -106013,7 +106002,7 @@
 5601: mph
 1007: )
 2012: at
-16480: cho
+10381: ch
 6182: ##shi
 1010: ,
 27368: chiba
@@ -106092,8 +106081,7 @@
 1999: in
 25933: ama
 4328: ##mi
-9808: os
-16369: ##hima
+24772: ##shima
 1010: ,
 1996: the
 4040: storm
@@ -106111,7 +106099,7 @@
 2006: on
 5292: ha
 5428: ##chi
-5558: ##jo
+3501: ##j
 1010: ,
 3612: wind
 26903: gust
@@ -108909,7 +108897,8 @@
 1997: of
 10101: rainfall
 1999: in
-27603: kochi
+1047: k
+5428: ##chi
 1010: ,
 2096: while
 2844: strong
@@ -132935,12 +132924,11 @@
 4351: designated
 1062: z
 2072: ##i
-29731: ##π
 2349: due
 2000: to
 1996: the
 1000: "
-1170: π
+100: [UNK]
 1000: "
 19587: topology
 1012: .
@@ -132953,7 +132941,7 @@
 1000: "
 2030: or
 1000: "
-1170: π
+100: [UNK]
 1000: "
 2930: section
 2003: is
@@ -133054,7 +133042,6 @@
 3372: ##nt
 1062: z
 2072: ##i
-29731: ##π
 1012: .
 2045: there
 2024: are
@@ -133716,7 +133703,7 @@
 1047: k
 1027: =
 1015: 1
-1179: ω
+100: [UNK]
 1012: .
 2023: this
 2003: is
@@ -133882,17 +133869,15 @@
 2003: is
 2170: called
 1037: a
-1170: π
+100: [UNK]
 2930: section
 1012: .
 2073: where
 1062: z
 2072: ##i
-29731: ##π
 5344: faces
 1062: z
 2072: ##i
-29731: ##π
 1996: the
 2930: section
 2061: so
@@ -147284,17 +147269,11 @@
 1693: ア
 30221: ##イ
 30257: ##ラ
-30246: ##フ
-30240: ##ト
 30241: ##ナ
 30259: ##ル
-30240: ##ト
-30235: ##タ
 30237: ##ッ
 30228: ##ク
-1702: ク
 30259: ##ル
-30232: ##シ
 30219: ##ア
 1909: 王
 1671: の
@@ -147314,10 +147293,10 @@
 2226: ##u
 11972: guru
 26541: ##jia
-1051: o
+100: [UNK]
 2053: no
 7632: hi
-6806: ##ho
+2232: ##h
 1007: )
 1010: ,
 2003: is
@@ -188846,7 +188825,8 @@
 1025: ;
 3763: latin
 1024: :
-19212: nero
+11265: ne
+2099: ##r
 25017: claudius
 11604: caesar
 11668: augustus
@@ -200556,7 +200536,9 @@
 29869: ##र
 29879: ##ो
 29863: ##न
+100: [UNK]
 1317: ग
+100: [UNK]
 1000: "
 2029: which
 2003: is
@@ -200633,7 +200615,11 @@
 29836: ##و
 29817: ##ت
 25573: ##ا
-100: [UNK]
+1282: س
+23673: ##ل
+29836: ##و
+15394: ##د
+29836: ##و
 23856: kota
 16183: sal
 6784: ##ud
@@ -226008,27 +225994,29 @@
 9973: pinyin
 1024: :
 2568: mind
-20391: ##ulu
+2140: ##l
 1025: ;
 21877: pe
+100: [UNK]
 1044: h
 1030: @
 1011: -
 1030: @
-1051: o
 2063: ##e
 1030: @
 1011: -
 1030: @
-10147: ji
+1046: j
 1024: :
 8026: bin
 1030: @
 1011: -
 1030: @
 2000: to
+100: [UNK]
 1011: -
 8840: lo
+100: [UNK]
 1007: )
 2003: is
 1037: a
@@ -233749,7 +233737,8 @@
 16107: ##nko
 10882: fi
 15000: ##lip
-9142: ##ovic
+4492: ##ov
+2072: ##i
 2165: took
 2058: over
 2004: as
@@ -233792,7 +233781,7 @@
 1997: of
 2175: go
 13102: ##sp
-2594: ##ic
+2072: ##i
 1998: and
 2379: near
 22889: sl
@@ -233869,7 +233858,7 @@
 21590: ##sko
 6819: vi
 6460: ##je
-3401: ##ce
+2063: ##e
 27885: ob
 18053: ##rane
 1516: –
@@ -234461,7 +234450,8 @@
 16107: ##nko
 10882: fi
 15000: ##lip
-9142: ##ovic
+4492: ##ov
+2072: ##i
 1010: ,
 10655: likewise
 1037: a
@@ -234636,7 +234626,8 @@
 1010: ,
 10882: fi
 15000: ##lip
-9142: ##ovic
+4492: ##ov
+2072: ##i
 2165: took
 2058: over
 3094: command
@@ -234694,7 +234685,7 @@
 2000: to
 2175: go
 13102: ##sp
-2594: ##ic
+2072: ##i
 1010: ,
 2073: where
 2009: it
@@ -234706,7 +234697,7 @@
 2491: control
 2175: go
 13102: ##sp
-2594: ##ic
+2072: ##i
 2114: against
 1996: the
 1046: j
@@ -234719,19 +234710,20 @@
 4123: battalion
 4110: captured
 22827: kan
-21335: ##iza
+2072: ##i
+2050: ##a
 10492: barracks
 1999: in
 2175: go
 13102: ##sp
-2594: ##ic
+2072: ##i
 1012: .
 2076: during
 4337: combat
 1999: in
 2175: go
 13102: ##sp
-2594: ##ic
+2072: ##i
 1010: ,
 2382: 30
 3629: troops
@@ -234744,8 +234736,8 @@
 1010: ,
 7197: assisted
 2011: by
-6735: luck
-2080: ##o
+11320: lu
+3683: ##ko
 11867: sp
 2226: ##u
 1010: ,
@@ -234756,7 +234748,7 @@
 2236: general
 19817: tr
 13006: ##aj
-3401: ##ce
+2063: ##e
 1047: k
 12096: ##rst
 6777: ##ev
@@ -234782,7 +234774,8 @@
 7333: deployed
 2000: to
 2777: met
-14733: ##kovic
+7724: ##kov
+2072: ##i
 2006: on
 2654: 28
 2255: october
@@ -234805,7 +234798,7 @@
 2000: to
 2175: go
 13102: ##sp
-2594: ##ic
+2072: ##i
 1010: ,
 1037: a
 2112: part
@@ -234887,7 +234880,7 @@
 14713: ##ija
 1058: v
 2721: ##la
-19053: ##cic
+2072: ##i
 4123: battalion
 2241: based
 1999: in
@@ -234948,7 +234941,7 @@
 21590: ##sko
 6819: vi
 6460: ##je
-3401: ##ce
+2063: ##e
 27885: ob
 18053: ##rane
 1516: –
@@ -235004,7 +234997,7 @@
 1996: the
 2181: area
 1997: of
-24053: ska
+2912: ##ka
 19892: ##br
 2078: ##n
 3900: ##ja
@@ -235067,20 +235060,20 @@
 7221: ban
 15333: je
 2721: ##la
-19053: ##cic
+2072: ##i
 4123: battalion
 1010: ,
 13523: mat
 14713: ##ija
 1058: v
 2721: ##la
-19053: ##cic
+2072: ##i
 4123: battalion
 1010: ,
 10768: fe
 20683: ##rdo
 10514: su
-19053: ##cic
+2072: ##i
 4123: battalion
 1998: and
 2112: part
@@ -254648,7 +254641,6 @@
 3747: influence
 1997: of
 2332: king
-1097: æ
 10760: ##the
 20850: ##lb
 19058: ##ald
@@ -257962,7 +257954,6 @@
 1999: in
 15522: cyrillic
 1024: :
-1194: п
 2080: ##o
 29742: ##д
 25529: ##в

[hiepxanh]

@cebtenzzre look like duplicate this issue? https://github.com/ggerganov/llama.cpp/issues/3502

there is a PR here https://github.com/ggerganov/llama.cpp/issues/4868 other watting for PR is drafting here https://github.com/ggerganov/llama.cpp/pull/5613#discussion_r1497483512

[superchargez]

so, now BERT based models supported?

[bobqianic]

We likely need to move all the tokenization-related code from llama.cpp to a separate file. Otherwise, the llama.cpp will become too messy.

[cebtenzzre]

@​cebtenzzre look like duplicate this issue? #​3502 #​4868 watting for PR #​4868

Possibly related, but keep in mind that BERT uses an entirely separate tokenizer implementation (wordpiece "WPM") from all other models (SentencePiece "SPM" or GPT-2 "BPE").

[iamlemec]

Is the SPM preprocessor also replacing accented characters? Seems like we should be able to reuse bits from that. Btw, in case it's useful for folks, I made a little Python function that prints out a color-coded token diff between our results and those from Huggingface (it goes through llama-cpp-python):

https://gist.github.com/iamlemec/52eaa4961762efb9c064b871a67f6cc6

The biggest instance I'm finding there is with dash variants like emdash. But basically still a case of replacing certain complex characters with their base forms.

[cebtenzzre]

A comment regarding this issue from @​apage43:

tokenizers bert normalizer's accent stripping is unicode "NFD" normalization, which transforms any accented chars into the "canonical decomposition" (here's where the lookup table comes in - for tokenizers the table comes from here) - the base char + accent codepoint form instead of the single-codepoint form, then just stripping any accent ("non-spacing mark") characters (another table)

[iamlemec]

That's very helpful @cebtenzzre! Opening a PR with this in a minute.

[hiepxanh]

@cebtenzzre can you take a look on new deploy to see the improvment? https://github.com/ggerganov/llama.cpp/pull/5740