Trizone by Naoki Inaba | Pedro's Works



	
The original japanese name "サントイッチ - santoitchi" is a wordplay on "サンドイッチ sandwich" and "サントイチ three and one".

Although this genre has been referred to as "Sandwich", @NaokiInaba wishes it be named "Trizone" in English, to preserve the wordplay. This name was chosen by @NaokiInaba as an English word also containing "three" and "one", with a thematic bonus of being an historical term about "region division".


## [trizone] puzzles

###@NaokiInaba
W=4x4&L=(2)2(4)5(1)1(3)5&G=trizone&A=NaokiInaba&T=Example&U=http://www.inabapuzzle.com/honkaku/san.pdf
W=6x6&L=(1)0(2)3(2)2(1)6(2)3(3)6(2)5(3)3(1)2(2)3&G=trizone&A=NaokiInaba&U=http://www.inabapuzzle.com/honkaku/san.pdf
W=7x7&L=(3)2(2)1(2)4(1)5(3)1(3)4(2)6(2)6(2)2(2)3(3)5(3)3(2)6&G=trizone&A=NaokiInaba&U=http://www.inabapuzzle.com/honkaku/san.pdf
W=8x8&L=(3)3(1)4(2)3(1)2(2)2(3)2(1)5(2)5(3)2(2)3(4)2(3)11(3)3(1)3(3)6(2)4(1)3&G=trizone&A=NaokiInaba&U=http://www.inabapuzzle.com/honkaku/san.pdf
W=9x9&L=(2)0(2)6(2)4(1)2(3)2(3)3(3)3(3)4(2)3(2)7(6)6(1)2(2)11(3)1(4)3(3)3(3)4(2)4(3)3(1)4(1)3&G=trizone&A=NaokiInaba&U=http://www.inabapuzzle.com/honkaku/san.pdf


### site.author

W=5x5&LF=z13z4z4z3&L=(0)2(1)2(2)3(2)2(0)2(2)5(4)7&SSE=3RRULU3U3DDRURDD11U2RU&G=trizone&A=Pedro&D=02/07/2023&T=example
W=9x7&LF=z13z28z6z4z2z6&L=y4y4y1y1y5y2y1y3y1y4y3y1y1y1y10y3y11y5y1&SSE=2RRDLD10UURDD2U10U5UU4RRD1RRRDL3URU9RDRDRD5UULDL3RRR8DRDR2UULULLLDDLULUURURDDLLLUL2UR&G=trizone&A=Pedro&D=2023-11-04&F=3&T=The_real_questions

### @AnuragSahay

#### Classic

W=7x7&L=x0x1x1x1x1x1x1x1x1x3x1x1x1(0)1x4x1(1)3(1)1x3x1(0)1(3)3x1x1x1x1x3x1x1x1x1x1x1x1x1x1&G=trizone&A=Anurag_sahay&D=2024-02-26&F=1&T=The_“odds”_are_against_symmetry
W=5x5&L=(2)0(0)4(2)6(2)3(2)1(1)6(2)1&G=trizone&A=Anurag_Sahay&D=2024-02-28&F=2
W=5x6&L=(2)0(2)5(3)4x2(2)1x4(0)1x4(2)3(2)4x1&G=trizone&A=Anurag_sahay&D=2024-02-29&F=2&T=Wasteland
W=6x6&L=x0(1)3(1)1(1)1(0)8(1)1y6(2)1y9y1y1(1)3&G=trizone&A=Anurag_sahay&D=2024-03-02&F=2&T=Quite_the_Trio

#### hex

V=hex

Using the ´´hex´´ variant:
W=4x4x4&L=x0x1x2(2)1(1)1(2)1x3(3)2x5(1)3(0)4(1)2(0)2x3(1)4x2&V=hex&G=trizone&A=Anurag_Sahay&D=2024-03-01&F=2



### @Pinkhoodie

W=7x12&LF=z0z7z4z5z13z5z8z2z4z9z7z8z2z6z2&L=(1)14(1)1(2)2(1)2(1)2(2)1(1)3(2)2(3)3(2)1(3)2(1)16(0)2(3)2(3)1(1)4(3)3(1)1(2)1(1)3(1)1(3)2(1)1&SSE=4RRDLDL2RR1RR4RDRDLL2URURDD15U8URU6UULD6R2RD10LULDDRD6UR1LLURR2LUL3UULDDDRURDR1RR1U7LUUU1UR4U15LLUU&G=trizone&A=PinkHoodie&D=2024-03-01&F=2&O=Enigmarch_2024&T=Beaten_Door


## Acknowledgements and Changes

**2023-06-22** Thanks to @bakpao, @Iori, @Wand125 and @NaokiInaba for discussion that eventually settled the genre's English name.
**2023-06-28** Thanks to @MartinEnder for help clarifying the rules and other aspects of this page, as well as requesting empty-tile marks and auto-borders around shaded cells
**2023-06-29** Thanks to @Bakpao for surfacing that empty crossed regions shouldn't be highlighted / undivided region outlines should be subtler
**2023-11-04** Fixed a regression found by @Solyu (lines can be drawn starting at the outer frame again)
**2023-11-04** Question marks were added, a variant by @PinkHoodie; and a new harder puzzle was included!
**2024-01-17** A recent regression (yesterday) found by @placeholder and @pinkhoodie was corrected - thank you! 
**2024-02-26** :::puzzletters @AnuragSahay sent a classic 7x7 - thank you!
**2024-02-28** The rule panels of [Trizone] were masterfully [modernised|../panels#modern] by @AnuragSahay, who sent a second, classic puzzle - thank you!
**2024-02-26** @AnuragSahay made a third classic [Trizone] - thank you!
**2024-03-02** :::puzzletters @PinkHoodie and @AnuragSahay sent ean a [Trizone] - thank you!
**2024-03-04** :::puzzletters @AnuragSahay sent a ´´hex ´´´ variant puzzle!