Cross Math by Erich Friedman


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@ErichFriedman's earliest published Cross Math puzzles date from 2008, in [Brain Games|https://erich-friedman.github.io/published/cross/index.html].

The difference between Rechtengitter and [Cross math] is that the later allows for inequalities and does not require all (intermediate) divisions to be integral.


## [Cross Math] Puzzles

### @ErichFriedman

The following sets by @ErichFriedman were kindly transcribed by @PinkHoodie:

#### 2010

This set was [first published in Brain Games 2010|https://erich-friedman.github.io/published/cross2/index.html]

W=4x4&L=(1)0(5)4(7)4x4(3)1(6)1(10)1&L-MATH=e0d1m1p2t1t1e1m1t1m2p1m1e1m1t1e2e1e1&LF=(5)1(1)1(6)1(7)2(4)1(3)1(9)2(2)1(8)1&G=cross-math&A=Erich_Friedman&B=PinkHoodie&D=2010-07-31&N=1&T=Cross_Math
W=4x4&L=(1)0(2)4(21)4x4(3)1(5)1(19)1&L-MATH=e0m1p1m2d1t1e1d1p1m2p1p1e1t1t1e2e1e1&LF=(9)1(8)1(2)1(5)2(4)1(6)1(1)2(3)1(7)1&G=cross-math&A=Erich_Friedman&B=PinkHoodie&D=2010-07-31&N=2&T=Cross_Math
W=4x4&L=(3)0(48)4(20)4x4(4)1(14)1(2)1&L-MATH=e0d1d1t2p1m1e1t1t1m2p1m1e1p1p1e2e1e1&LF=(3)1(1)1(9)1(4)2(6)1(2)1(8)2(7)1(5)1&G=cross-math&A=Erich_Friedman&B=PinkHoodie&D=2010-07-31&N=3&T=Cross_Math
W=4x4&L=(5)0(13)4(47)4x4(12)1(59)1(13)1&L-MATH=e0d1p1p2t1p1e1p1p1p2p1p1e1p1t1e2e1e1&LF=(2)1(9)1(1)1(3)2(6)1(4)1(7)2(5)1(8)1&G=cross-math&A=Erich_Friedman&B=PinkHoodie&D=2010-07-31&N=4&T=Cross_Math
W=4x4&L=(24)0(1)4(24)4x4(17)1(15)1(13)1&L-MATH=e0p1t1p2p1p1e1m1p1p2p1p1e1t1p1e2e1e1&LF=(6)1(9)1(2)1(8)2(5)1(4)1(3)2(1)1(7)1&G=cross-math&A=Erich_Friedman&B=PinkHoodie&D=2010-07-31&N=5&T=Cross_Math
W=4x4&L=(2)0(2)4(2)4x4(2)1(4)1(2)1&L-MATH=e0m1t1p2m1t1e1d1p1d2m1d1e1d1t1e2e1e1&LF=(7)1(9)1(1)1(5)2(2)1(8)1(6)2(3)1(4)1&G=cross-math&A=Erich_Friedman&B=PinkHoodie&D=2010-07-31&N=6&T=Cross_Math
W=4x4&L=(5)0(0)4(8)4x4(12)1(10)1(0)1&L-MATH=e0m1p1d2d1p1e1m1m1p2p1m1e1p1m1e2e1e1&LF=(5)1(4)1(6)1(1)2(2)1(3)1(7)2(8)1(9)1&G=cross-math&A=Erich_Friedman&B=PinkHoodie&D=2010-07-31&N=7&T=Cross_Math
W=4x4&L=(16)0(3)4(1)4x4(13)1(12)1(2)1&L-MATH=e0p1p1p2p1p1e1d1p1p2t1d1e1m1d1e2e1e1&LF=(6)1(1)1(9)1(4)2(5)1(7)1(3)2(2)1(8)1&G=cross-math&A=Erich_Friedman&B=PinkHoodie&D=2010-07-31&N=8&T=Cross_Math
W=4x4&L=(15)0(15)4(0)4x4(15)1(15)1(15)1&L-MATH=e0p1p1p2t1t1e1p1t1p2m1p1e1m1m1e2e1e1&LF=(5)1(2)1(8)1(6)2(9)1(1)1(4)2(3)1(7)1&G=cross-math&A=Erich_Friedman&B=PinkHoodie&D=2010-07-31&N=9&T=Cross_Math
W=4x4&L=(0)0(36)4(48)4x4(19)1(13)1(2)1&L-MATH=e0m1m1p2t1m1e1t1p1p2p1m1e1t1p1e2e1e1&LF=(6)1(2)1(8)1(9)2(3)1(1)1(4)2(7)1(5)1&G=cross-math&A=Erich_Friedman&B=PinkHoodie&D=2010-07-31&N=10&T=Cross_Math


#### 2008

This set was [first published in Brain Games 2008|https://erich-friedman.github.io/published/cross/index.html]

W=4x4&L=(3)0(12)4(4)4x4(14)1(24)1(15)1&L-MATH=e0m1p1p2p1p1e1m1t1m2t1p1e1d1d1e2e1e1&LF=(6)1(5)1(4)1(9)2(7)1(3)1(1)2(2)1(8)1&G=cross-math&A=Erich_Friedman&B=PinkHoodie&D=2008-01-31&N=1&T=Cross_Math
W=4x4&L=(2)0(10)4(14)4x4(2)1(66)1(1)1&L-MATH=e0d1p1m2t1m1e1t1p1m2m1d1e1m1t1e2e1e1&LF=(7)1(9)1(5)1(1)2(8)1(2)1(4)2(6)1(3)1&G=cross-math&A=Erich_Friedman&B=PinkHoodie&D=2008-01-31&N=2&T=Cross_Math
W=4x4&L=(8)0(10)4(4)4x4(16)1(26)1(9)1&L-MATH=e0m1p1p2t1p1e1p1d1p2p1d1e1m1p1e2e1e1&LF=(4)1(9)1(3)1(7)2(2)1(6)1(5)2(8)1(1)1&G=cross-math&A=Erich_Friedman&B=PinkHoodie&D=2008-01-31&N=3&T=Cross_Math
W=4x4&L=(17)0(15)4(3)4x4(26)1(18)1(9)1&L-MATH=e0p1p1p2p1m1e1p1p1t2t1p1e1m1m1e2e1e1&LF=(9)1(1)1(7)1(4)2(5)1(6)1(2)2(3)1(8)1&G=cross-math&A=Erich_Friedman&B=PinkHoodie&D=2008-07-31&N=4&T=Cross_Math
W=4x4&L=(21)0(4)4(20)4x4(12)1(21)1(2)1&L-MATH=e0t1t1p2p1p1e1m1p1p2p1d1e1t1p1e2e1e1&LF=(1)1(7)1(3)1(9)2(8)1(5)1(2)2(6)1(4)1&G=cross-math&A=Erich_Friedman&B=PinkHoodie&D=2008-01-31&N=5&T=Cross_Math
W=4x4&L=(10)0(6)4(2)4x4(10)1(2)1(6)1&L-MATH=e0p1p1d2t1p1e1p1m1p2m1m1e1d1p1e2e1e1&LF=(3)1(2)1(5)1(1)2(4)1(9)1(7)2(6)1(8)1&G=cross-math&A=Erich_Friedman&B=PinkHoodie&D=2008-01-31&N=6&T=Cross_Math
W=4x4&L=(6)0(9)4(11)4x4(11)1(15)1(11)1&L-MATH=e0t1d1p2p1p1e1p1d1m2p1m1e1p1p1e2e1e1&LF=(9)1(6)1(4)1(5)2(2)1(8)1(3)2(7)1(1)1&G=cross-math&A=Erich_Friedman&B=PinkHoodie&D=2008-01-31&N=7&T=Cross_Math
W=4x4&L=(3)0(12)4(6)4x4(20)1(20)1(2)1&L-MATH=e0d1p1p2t1m1e1p1p1p2p1d1e1m1t1e2e1e1&LF=(5)1(8)1(7)1(9)2(2)1(1)1(6)2(4)1(3)1&G=cross-math&A=Erich_Friedman&B=PinkHoodie&D=2008-01-31&N=8&T=Cross_Math
W=4x4&L=(24)0(5)4(24)4x4(24)1(6)1(24)1&L-MATH=e0p1t1m2p1p1e1m1p1t2m1t1e1t1p1e2e1e1&LF=(9)1(3)1(5)1(6)2(4)1(7)1(8)2(1)1(2)1&G=cross-math&A=Erich_Friedman&B=PinkHoodie&D=2008-01-31&N=9&T=Cross_Math
W=4x4&L=(10)0(7)4(18)4x4(25)1(8)1(17)1&L-MATH=e0m1t1t2d1p1e1p1d1m2p1p1e1p1p1e2e1e1&LF=(8)1(2)1(9)1(4)2(1)1(3)1(7)2(6)1(5)1&G=cross-math&A=Erich_Friedman&B=PinkHoodie&D=2008-01-31&N=10&T=Cross_Math
W=4x4&L=(10)0(11)4(10)4x4(10)1(10)1(10)1&L-MATH=e0m1p1t2p1p1e1p1m1m2p1m1e1p1m1e2e1e1&LF=(2)1(5)1(7)1(9)2(4)1(6)1(8)2(1)1(3)1&G=cross-math&A=Erich_Friedman&B=PinkHoodie&D=2008-01-31&N=11&T=Cross_Math
W=4x4&L=(3)0(4)4(20)4x4(4)1(24)1(2)1&L-MATH=e0p1m1m2t1p1e1m1m1p2t1d1e1t1p1e2e1e1&LF=(6)1(8)1(5)1(4)2(1)1(9)1(2)2(3)1(7)1&G=cross-math&A=Erich_Friedman&B=PinkHoodie&D=2008-01-31&N=12&T=Cross_Math
W=4x4&L=(5)0(2)4(3)4x4(19)1(18)1(17)1&L-MATH=e0m1p1t2t1t1e1m1p1p2p1p1e1d1p1e2e1e1&LF=(7)1(4)1(8)1(2)2(3)1(1)1(5)2(6)1(9)1&G=cross-math&A=Erich_Friedman&B=PinkHoodie&D=2008-01-31&N=13&T=Cross_Math

#### Numbers Puzzles

@JustKirb kindly transcribed the following [Numbers Puzzles|https://erich-friedman.github.io/puzzle/number], after noticing they were part indeed like this genre:
W=3x3&L=x6&L-MATH=e0p1p2d1e1t1e2e1&G=cross-math&A=Erich_Friedman&B=justkirb&F=1&N=1&O=This_puzzle_set_is_a_consequence_of_similar_rulesets.&T=Number_Puzzles_3x3&U=erich-friedman.github.io/puzzle/number/
W=4x3&L=x9&L-MATH=e0p1t2t1e1d1m2p1e1p1e2e1&G=cross-math&A=Erich_Friedman&B=justkirb&F=3&N=2&T=Number_Puzzles_3x4&U=erich-friedman.github.io/puzzle/number/
W=4x4&L=x12&L-MATH=e0m1p1t2p1p1e1d1d1t2m1m1e1p1p1e2e1e1&G=cross-math&A=Erich_Friedman&B=justkirb&F=4&N=3&T=Number_Puzzles_4x4&U=erich-friedman.github.io/puzzle/number/


### @AnuragSahay

W=4x4&L=(16)0(26)4(3)4x4(12)1(21)1(32)1&L-MATH=e0p1p1m2t1t1e1t1p1p2d1p1e1m1d1e2e1e1&G=cross-math&A=Anurag&D=2024-06-20&F=3

### @Pinkhoodie

W=4x4&L=(2)0(0)4(11)4x4(5)1(5)1(9)1&L-MATH=e0d1d1m2d1p1e1m1m1p2p1m1e1p1d1e2e1e1&LF=(1)1(4)1(8)1(5)2(2)1(7)1(9)2(3)1(6)1&G=cross-math&A=PinkHoodie&D=2024-06-19&F=2&T=Split_Chai

### @Pedro

W=4x4&L=(14)0(7)4(4)4x4(40)1(21)1(2)1&L-MATH=e0t1t1p2p1t1e1m1p1t2p1d1e1m1p1e2e1e1&LF=(2)1(7)1(1)1(8)2(9)1(6)1(4)2(5)1(3)1&G=cross-math&A=Pedro&D=2024-06-20

## Acknowledgements and Changes
**2024-06-18** Thanks to @AnuragSahay for collaborating in the making of the [rule panels|../panels], and sharing a puzzle for the rollout!
**2024-06-19** Thanks to @PinkHoodie for taking the initiative and diligently transcribing the original sets by @ErichFriedman, and for sending a rollout puzzle! 
**2024-06-20** @Anurag's puzzle was using an incorrect link - corrected.
**2024-06-28** Three Numbers Puzzles were discovered and kindly transcribed by @JustKirb. Thank you!
**2024-08-06** An equation parsing bug was corrected (cause: the equation-to-sequential transformation was incomplete, especially for equations in reverse order)