Tough Sudoku for 23/December/2018

Basics to 24
1. (9)i12=i8-(9=1)g7-(14=8)c37-(8=4679)g13.hi1 =>-9g2.h23
2. (9)h5=g5-g3=(9-2)d3=(2)h3 =>-2h5; basics to 38
3. (2=9)d2-d3=g3-i12=(9-3)i8=(3)i2 =>-2i2; basics to 40
4. (1)b8=(1-5)g8=(5-8)g2=(8)b2 =>-1b2; basics to 81

14:32.

1:25:22

SE=9.0
Basics to UP=24
1)(8=3)i9-(3=36)a9ac8-(2)a8=a6-i6=(2)i2*-h3=(2-9)d3=gh3-i12=(9)i8,=>i28<>8
2)AUR(58 )gh28:(8)i9=(8)gh3-(8=4)c3-(4=1)c7-(1=9)g7-(9=3)i8,=>i9<>3
3)(47=9)i41-hg3=(9-2)d3=h3-i2=( 2)i6,=>i6<>47
4)(19=1)a12b2-b8=(1-5)g8=(5-8)g2=g3-(8=4)c3,=>a12<>4.UP=81

#25 1?@a9=>c7=4=>29@b78=>h5=2=>d3=2=>d2=9=>a2=4=>c3=8=>17@bc2=>34@e23=>e5 =1=>e3=4=>g3=9=>a….i5<>9=>a9<>1
#35 2?@h5=>{g5=9=>g7=1=>g8=5,i2=2=>i8=3}=>h8=9=>d3=9=>a….i3<>2=>h5<> ;2
#39 9?@d2=>a1=9=>{h1=6,47@i14=>i6=2}=>h6=1=>a4=1=>b2=1=>b8=9=>i1….9<>9=&G T;d2<>9
#45 9?@b8=>i8=3=>h2=3=>g2=5=>b2=8=>c3=4=>c7=1=>b6=1=>h6==>h1=9=>g5=9=> g7={}=>b8<>9

1. Unique possibilities to 24.
Making use of 3 Unresolvable Rectangles in 2 steps:
2. Whether d3=9,h3=2;d2=9=a1=i8,g7=1=f1,c7=4=ab2,e2=3=i9,i2=8(or else 58UR @ gh28);i6=2.UP40.
3. Whether a4=6=h6;OR a4=1=f1=c7,g7=9,i8=3,i1=7(or else 49UR @ ai12),g4=7,h4=6(or else 48UR @ df58);h1=9.UP81.

In step 2, should read: ......h3=2; OR......

Also, Cenoman's step 4 is much neater and shorter than my step 3.

Basics to 24
1.X-chain x=2 =>[d9,f2]<>2
2. if d3=2 => d2=9 a1=9 h1=6 hi1=47 i8=9 g7=1
c7=4 c3=8 e3=4 e2=3=h3=i9 g3=9 i4=8 i2=2
UR58 gh28 => h3=2 Basics to 44
3.UR 47 gi14 => a1<>9 => a2=9 Basics to 45
4.XY-chain 1349 [b8,i8,i2,e2]=> b2<>1 a1=1
solve