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As a first step:

sage: p=posets.PentagonPoset()
sage: Q=DiGraph([(x,y,'c'+str(x)+str(y)) for x,y in p.cover_relations()])
sage: Q.path_semigroup().algebra(QQ)
Path algebra of Digraph on 5 vertices over Rational Field

Then you need a general way to pass this path algebra and its elements to gap.

As a first step:

sage: p=posets.PentagonPoset()
sage: Q=DiGraph([(x,y,'c'+str(x)+str(y)) for x,y in p.cover_relations()])
sage: Q.path_semigroup().algebra(QQ)
Path algebra of Digraph on 5 vertices over Rational Field

Then you need a general way to pass this path algebra and its elements to gap.

EDIT

Here is an helper function:

def gap_text(P):
    Q = DiGraph([(x,y,'x'+str(x)+str(y)) for x, y in P.cover_relations()])
    SG = Q.path_semigroup()
    A = SG.algebra(ZZ)
    rels = []
    for a, b in P.relations():
        if Q.in_degree(b) > 1 and Q.out_degree(a) > 1:
            paths = Q.all_paths(a, b)
            if len(paths) > 1:
                prod_paths = [A.prod(A(Q.edge_label(pa[i], pa[i+1]))
                                      for i in range(len(pa) - 1))
                              for pa in paths]
                rels += [prod_paths[0] - pi for pi in prod_paths[1:]]
    txt0 = 'Q:=Quiver({},{});'.format(Q.size(),Q.edges())
    txt1 = 'kQ:=PathAlgebra(Rationals,Q);'
    txt2 = 'AssignGeneratorVariables(kQ);'
    txt3 = 'rel:={};'.format(rels)
    txt4 = 'A:=kQ/rel;'
    return txt0 + txt1 + txt2 + txt3 + txt4

that gives

sage: p=posets.DivisorLattice(6)
sage: gap_text(p)
"Q:=Quiver(4,[(1, 2, 'x12'), (1, 3, 'x13'), (2, 6, 'x26'), (3, 6, 'x36')]);kQ:=PathAlgebra(Rationals,Q);AssignGeneratorVariables(kQ);rel:=[-x13*x36 + x12*x26];A:=kQ/rel;"

As a first step:

sage: p=posets.PentagonPoset()
sage: Q=DiGraph([(x,y,'c'+str(x)+str(y)) for x,y in p.cover_relations()])
sage: Q.path_semigroup().algebra(QQ)
Path algebra of Digraph on 5 vertices over Rational Field

Then you need a general way to pass this path algebra and its elements to gap.

EDIT

Here is an a better helper function:

def gap_text(P):
    Z = P.relabel()
    Z = Z.relabel(lambda s: s+1)
    Q = DiGraph([(x,y,'x'+str(x)+str(y)) for x, y in P.cover_relations()])
Z.cover_relations()])
    SG = Q.path_semigroup()
    A = SG.algebra(ZZ)
    rels = []
    for a, b in P.relations():
Z.relations():
        if Q.in_degree(b) > 1 and Q.out_degree(a) > 1:
            paths = Q.all_paths(a, b)
            if len(paths) > 1:
                prod_paths = [A.prod(A(Q.edge_label(pa[i], pa[i+1]))
                                      for i in range(len(pa) - 1))
                              for pa in paths]
                rels += [prod_paths[0] - pi for pi in prod_paths[1:]]
    txt0 = 'Q:=Quiver({},{});'.format(Q.size(),Q.edges())
'Q:=Quiver({},{});'.format(Q.size(),[list(e) for e in Q.edges()])
    txt1 = 'kQ:=PathAlgebra(Rationals,Q);'
    txt2 = 'AssignGeneratorVariables(kQ);'
    txt3 = 'rel:={};'.format(rels)
    txt4 = 'A:=kQ/rel;'
    return txt0 + txt1 + txt2 + txt3 + txt4

that gives

sage: p=posets.DivisorLattice(6)
sage: gap_text(p)
"Q:=Quiver(4,[(1, 2, 'x12'), (1, 3, 'x13'), (2, 6, 'x26'), (3, 6, 'x36')]);kQ:=PathAlgebra(Rationals,Q);AssignGeneratorVariables(kQ);rel:=[-x13*x36 + x12*x26];A:=kQ/rel;"

As a first step:

sage: p=posets.PentagonPoset()
sage: Q=DiGraph([(x,y,'c'+str(x)+str(y)) for x,y in p.cover_relations()])
sage: Q.path_semigroup().algebra(QQ)
Path algebra of Digraph on 5 vertices over Rational Field

Then you need a general way to pass this path algebra and its elements to gap.

EDIT

Here is a better helper function:

def gap_text(P):
    Z = P.relabel()
    Z = Z.relabel(lambda s: s+1)
    Q = DiGraph([(x,y,'x'+str(x)+str(y)) for x, y in Z.cover_relations()])
    SG = Q.path_semigroup()
    A = SG.algebra(ZZ)
    rels = []
    for a, b in Z.relations():
        if Q.in_degree(b) > 1 and Q.out_degree(a) > 1:
            paths = Q.all_paths(a, b)
            if len(paths) > 1:
                prod_paths = [A.prod(A(Q.edge_label(pa[i], pa[i+1]))
                                      for i in range(len(pa) - 1))
                              for pa in paths]
                rels += [prod_paths[0] - pi for pi in prod_paths[1:]]
    txt0 = 'Q:=Quiver({},{});'.format(Q.size(),[list(e) 'Q:=Quiver({},{});'.format(Q.num_verts(),[list(e) for e in Q.edges()])
    txt1 = 'kQ:=PathAlgebra(Rationals,Q);'
    txt2 = 'AssignGeneratorVariables(kQ);'
    txt3 = 'rel:={};'.format(rels)
    txt4 = 'A:=kQ/rel;'
    return txt0 (txt0 + txt1 + txt2 + txt3 + txt4
txt4).replace("'", '"')

that gives

sage: p=posets.DivisorLattice(6)
sage: gap_text(p)
"Q:=Quiver(4,[(1, 2, 'x12'), (1, 3, 'x13'), (2, 6, 'x26'), (3, 6, 'x36')]);kQ:=PathAlgebra(Rationals,Q);AssignGeneratorVariables(kQ);rel:=[-x13*x36 + x12*x26];A:=kQ/rel;"