Find additional algorithmic restrictions on motorcycle join operations

[julialongtin]

broken in 6b97dd3.

Wrong:
Algebra(2,0,1,()=>{
var line = (a,b,c)=>a1e1 + b1e2 + c1e0;
var point = (x,y)=>!(1e0 + x1e1 + y*1e2);
var aaa = point(-1.0,1.0);
var aab = point(-1.0,-1.0);
var aba = point(-1.0,-1.0);
var abb = point(-0.5,-1.0);
var aca = point(-0.5,-1.0);
var acb = point(0.0,0.0);
var ada = point(0.0,0.0);
var adb = point(0.5,-1.0);
var aea = point(0.5,-1.0);
var aeb = point(1.0,-1.0);
var afa = point(1.0,-1.0);
var afb = point(1.0,1.0);
var aga = point(1.0,1.0);
var agb = point(-1.0,1.0);
var aha = 0.7071067811865475e1-0.7071067811865475e2+0.0e0;
var ahb = 0.8506508083520399e1+0.5257311121191337e2+0.9510565162951536e0;
var ahc = 0.9932897335288758e1-0.11565251949756605e2+0.606432399999752e0;
var aia = -0.7071067811865475e1-0.7071067811865475e2+0.0e0;
var aib = 0.9932897335288758e1-0.11565251949756605e2+0.606432399999752e0;
var aic = 0.5257311121191336e1-0.8506508083520399e2+0.5877852522924731e0;
var aja = 0.8506508083520399e1-0.5257311121191337e2-0.9510565162951536e0;
var ajb = 0.7071067811865475e1+0.7071067811865475e2+0.0e0;
var ajc = 0.9932897335288758e1+0.11565251949756605e2-0.606432399999752e0;
var aka = 0.9932897335288758e1+0.11565251949756605e2-0.606432399999752e0;
var akb = -0.7071067811865475e1+0.7071067811865475e2+0.0e0;
var akc = 0.5257311121191336e1+0.8506508083520399e2-0.5877852522924731e0;
var ala = 0.5257311121191336e1-0.8506508083520399e2+0.5877852522924731e0;
var alb = 1.0e1+0.0e2+0.0e0;
var alc = 0.5257311121191336e1+0.8506508083520399e2-0.5877852522924731e0;
document.body.appendChild(this.graph([
0x882288,
[aaa,aab],
0x00AA88,
aaa, "aaa",
aab, "aab",
0x882288,
[aba,abb],
0x00AA88,
aba, "aba",
abb, "abb",
0x882288,
[aca,acb],
0x00AA88,
aca, "aca",
acb, "acb",
0x882288,
[ada,adb],
0x00AA88,
ada, "ada",
adb, "adb",
0x882288,
[aea,aeb],
0x00AA88,
aea, "aea",
aeb, "aeb",
0x882288,
[afa,afb],
0x00AA88,
afa, "afa",
afb, "afb",
0x882288,
[aga,agb],
0x00AA88,
aga, "aga",
agb, "agb",
aha, "aha",
ahb, "ahb",
ahc, "ahc",
aia, "aia",
aib, "aib",
aic, "aic",
aja, "aja",
ajb, "ajb",
ajc, "ajc",
aka, "aka",
akb, "akb",
akc, "akc",
ala, "ala",
alb, "alb",
alc, "alc",
],{
grid: true,
labels: true,
lineWidth: 3,
pointRadius: 1,
fontSize: 1,
scale: 1,
}));
});

Right:
Algebra(2,0,1,()=>{
var line = (a,b,c)=>a1e1 + b1e2 + c1e0;
var point = (x,y)=>!(1e0 + x1e1 + y*1e2);
var aaa = point(-1.0,1.0);
var aab = point(-1.0,-1.0);
var aba = point(-1.0,-1.0);
var abb = point(-0.5,-1.0);
var aca = point(-0.5,-1.0);
var acb = point(0.0,0.0);
var ada = point(0.0,0.0);
var adb = point(0.5,-1.0);
var aea = point(0.5,-1.0);
var aeb = point(1.0,-1.0);
var afa = point(1.0,-1.0);
var afb = point(1.0,1.0);
var aga = point(1.0,1.0);
var agb = point(-1.0,1.0);
var aha = 0.7071067811865475e1-0.7071067811865475e2+0.0e0;
var ahb = 0.8506508083520399e1+0.5257311121191337e2+0.9510565162951536e0;
var ahc = 0.9932897335288758e1-0.11565251949756612e2+0.606432399999752e0;
var aia = 0.8506508083520399e1-0.5257311121191337e2-0.9510565162951536e0;
var aib = 0.7071067811865475e1+0.7071067811865475e2+0.0e0;
var aic = 0.9932897335288758e1+0.11565251949756612e2-0.606432399999752e0;
var aja = -0.7071067811865475e1-0.7071067811865475e2+0.0e0;
var ajb = 0.9932897335288758e1-0.11565251949756612e2+0.606432399999752e0;
var ajc = 0.46640281702659836e1-1.7696651604731914e2+1.2228085515337068e0;
var aka = 0.9932897335288758e1+0.11565251949756612e2-0.606432399999752e0;
var akb = -0.7071067811865475e1+0.7071067811865475e2+0.0e0;
var akc = 0.4664028170265986e1+1.7696651604731914e2-1.2228085515337068e0;
var ala = 0.46640281702659836e1-1.7696651604731914e2+1.2228085515337068e0;
var alb = 1.7888543819998317e1+0.0e2+0.0e0;
var alc = 0.4664028170265986e1+1.7696651604731914e2-1.2228085515337068e0;
document.body.appendChild(this.graph([
0x882288,
[aaa,aab],
0x00AA88,
aaa, "aaa",
aab, "aab",
0x882288,
[aba,abb],
0x00AA88,
aba, "aba",
abb, "abb",
0x882288,
[aca,acb],
0x00AA88,
aca, "aca",
acb, "acb",
0x882288,
[ada,adb],
0x00AA88,
ada, "ada",
adb, "adb",
0x882288,
[aea,aeb],
0x00AA88,
aea, "aea",
aeb, "aeb",
0x882288,
[afa,afb],
0x00AA88,
afa, "afa",
afb, "afb",
0x882288,
[aga,agb],
0x00AA88,
aga, "aga",
agb, "agb",
aha, "aha",
ahb, "ahb",
ahc, "ahc",
aia, "aia",
aib, "aib",
aic, "aic",
aja, "aja",
ajb, "ajb",
ajc, "ajc",
aka, "aka",
akb, "akb",
akc, "akc",
ala, "ala",
alb, "alb",
alc, "alc",
],{
grid: true,
labels: true,
lineWidth: 3,
pointRadius: 1,
fontSize: 1,
scale: 1,
}));