LUklbXJvd0c2Iy9JK21vZHVsZW5hbWVHNiJJLFR5cGVzZXR0aW5nR0koX3N5c2xpYkdGJzYjLUkjbWlHRiQ2I1EhRic=Series expansion for rooted quadrangulations endowed with dimersrestart:The order N of the Taylor expansion, N:=10:
R:=0:
for i from 1 to N do
R:=series(expand(convert(series(1+3*z*R^2+9*z^2*w*R^5,z,i+1),polynom)),z,i+1):
od:The development of Q up to order N, with weight z per face and w per dimerQ:=series(expand(convert(series(R-1-z*R^3-6*w*z^2*R^6,z,i+1),polynom)),z,N+1);Series expansion for rooted triangulations endowed with dimersrestart:The order N of the Taylor expansion, N:=10:
S:=0:
for i from 1 to N do
S:=series(expand(convert(series((1-8*z*S-48*w*z^2*S^5)^(-1/2),z,i+1),polynom)),z,i+1):
od:The development of T up to order N, with weight z per non-root vertex and w per dimerT:=series(expand(convert(series((S-1)/(2*S)-z-z*S^2-10*w*z^2*S^6,z,i+1),polynom)),z,N+1);Critical dimer-weight for rooted quadrangulationsFinding the tri-crical singular point and the singular expansionrestart:The generating function is expressed in terms of R=1+3z R^2+9w z^2 R^5Eq_R:=-R+1+3*z*R^2+9*w*z^2*R^5;We now look for w such that the singularity is tri-critical (not only are Eq_R and diff(Eq_R,R) zero, but also diff(Eq_R,R,R)) solve({Eq_R,diff(Eq_R,R),diff(Eq_R,R,R)},{R,z,w});Now, for w=-3/125, we find the singular development of R(z) around the singularity z0=4/45, with the notation Z=(z0-z)^(1/3) (in the associated article we use the notationZ=z0-z). We already know that c[0]=5/2 from the above w:=-3/125: z0:=4/45: z:=z0-Z^3: N:=4: R:=add(c[i]*Z^i,i=0..N); c[0]:=5/2: Since Eq_R=0, the next series development in Z has to cancel out at each order in Z, this allows to determine the coefficients c[i] order by order in isimplify(series(Eq_R,Z,N+3));solve(-15-(8/75)*c[1]^3);c[1]:=-(5/2)*3^(2/3);for i from 2 to 4 do
c[i]:=solve(coeff(simplify(series(Eq_R,Z,N+3)),Z,i+2));
od:We obtain thus the singular development of R in terms of Z, up to the term Z^4R;We now obtain the singular development for Q, and we see cancellations of the terms in Z and Z^2 (Z^3 is not singular since it is z0-z), so that the first singular term is Z^4Q:=series(R-1-z*R^3-6*z^2*w*R^6,Z,5);Checking that the singularity is dominantrestart:Digits:=50;w:=-3/125;Eq_R:=-R+1+3*z*R^2+9*w*z^2*R^5;The roots of the following polynomial are the candidate singularities at w=-3/125factor(resultant(Eq_R,diff(Eq_R,R),R));evalf(4/45); evalf(-4/15);The order N of the Taylor expansion, N:=120:
R:=0:
for i from 1 to N do
R:=series(expand(convert(series(1+3*z*R^2+9*z^2*w*R^5,z,i+1),polynom)),z,i+1):
od:R:We see that the ratio of two consecutive coefficients converges slowly to 4/45seq(evalf(coeff(R,z,i)/coeff(R,z,i+1)),i=N-10..N-1);Critical dimer-weight for rooted triangulationsFinding the tri-crical singular point and the singular expansionrestart:The generating function is expressed in terms of S^2=1+8z S^3+48w z^2 S^7Eq_S:=-S^2+1+8*z*S^3+48*w*z^2*S^7;We now look for w such that the singularity is tri-critical (not only are Eq_S and diff(Eq_S,S) zero, but also diff(Eq_S,S,S)) solve({Eq_S,diff(Eq_S,S),diff(Eq_S,S,S)},{S,z,w});Now, for w=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, we find the singular development of S(z) around the singularity z0=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, with the notation Z=(z0-z)^(1/3) (in the associated article we use the notation Z=z0-z). We already know that c[0]=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 from the above w:=-(8/1029)*RootOf(5*_Z^2-21): z0:=(25/1008)*RootOf(5*_Z^2-21): z:=z0-Z^3: N:=4: S:=add(c[i]*Z^i,i=0..N); c[0]:=RootOf(5*_Z^2-21): Since Eq_S=0, the next series development in Z has to cancel out at each order in Z, this allows to determine the coefficients c[i] order by order in isimplify(series(Eq_S,Z,N+3));solve(625*c[1]^3+43848);c[1]:=-(6/25)*5075^(1/3);for i from 2 to 4 do
c[i]:=solve(coeff(simplify(series(Eq_S,Z,N+3)),Z,i+2));
od:We obtain thus the singular development of S in terms of Z, up to the term Z^4S;We now obtain the singular development for T, and we see cancellations of the terms in Z and Z^2 (Z^3 is not singular since it is z0-z), so that the first singular term is Z^4T:=simplify(series((S-1)/(2*S)-z-z*S^2-10*w*z^2*S^6,Z,5));Checking that the singularity is dominantrestart:Digits:=50;w:=-8/1029*sqrt(21/5);Eq_S:=-S^2+1+8*z*S^3+48*w*z^2*S^7;The candidate singularites are the roots of the following polynomialfactor(resultant(Eq_S,diff(Eq_S,S),S));fsolve((70672*sqrt(105)*z^2+5017600*z^3+125*sqrt(105)+50400*z)*(-1008*z+5*sqrt(105)));w:=evalf(-8/1029*sqrt(21/5));The order N of the Taylor expansion, N:=80:
S:=0:
for i from 1 to N do
S:=series(expand(convert(series((1-8*z*S-48*w*z^2*S^5)^(-1/2),z,i+1),polynom)),z,i+1):
od:S:We see that the ratio of two consecutive coefficients converges slowly to LUklbXJvd0c2Iy9JK21vZHVsZW5hbWVHNiJJLFR5cGVzZXR0aW5nR0koX3N5c2xpYkdGJzYmLUkjbW5HRiQ2JFEoMC4wNTA4MkYnLyUsbWF0aHZhcmlhbnRHUSdub3JtYWxGJy1JI21vR0YkNi1RIy4uRidGLy8lJmZlbmNlR1EmZmFsc2VGJy8lKnNlcGFyYXRvckdGOC8lKXN0cmV0Y2h5R0Y4LyUqc3ltbWV0cmljR0Y4LyUobGFyZ2VvcEdGOC8lLm1vdmFibGVsaW1pdHNHRjgvJSdhY2NlbnRHRjgvJSdsc3BhY2VHUSwwLjIyMjIyMjJlbUYnLyUncnNwYWNlR1EmMC4wZW1GJy1GMzYtUSIuRidGL0Y2RjlGO0Y9Rj9GQUZDL0ZGRkpGSEYvseq(evalf(coeff(S,z,i)/coeff(S,z,i+1)),i=N-10..N-1);LUklbXJvd0c2Iy9JK21vZHVsZW5hbWVHNiJJLFR5cGVzZXR0aW5nR0koX3N5c2xpYkdGJzYjLUkjbWlHRiQ2I1EhRic=