From CTE in SQL for relational algebra

How to pass a CTE in SQL to relational algebra, such as:

with publicacao_cte (nome,nr_publicacoes) 
AS 
( 
select 
candidato.nome, 
Count(1) as nr_publicacoes 
from 
candidato, 
cv, 
ficha_inscricao, 
publicacao_cv 
where 
candidato.bi = ficha_inscricao.bi and 
candidato.bi = cv.bi and 
cv.cod_cv = publicacao_cv.cod_cv 
group by candidato.nome
) 

I would also like to know how to do group by and order by in relational algebra.