Who is entitled to half-price tickets?

In the state of São Paulo, half-price tickets are regulated by a set of federal and state laws and decrees. See here if you meet one of the conditions:

Students – Federal Law 12.933/13, Federal Decree 8.537/15.
What to bring: Student Identification Card – CIE – a document issued by the National Association of Postgraduate Students (ANPG), the National Union of Students (UNE), the Brazilian Union of Secondary School Students (Ubes), state and municipal entities affiliated with them, Central Student Directories (DCEs), and Academic Centers and Directories, which proves the status of a student regularly enrolled in the levels and modalities of education and teaching provided for in Title V of Law No. 9,394 of 1996, according to a single nationally standardized model, with digital certification and which may have fifty percent local characteristics.
The wallet should contain the following items: Full name and date of birth of the student; recent photo of the student; name of the educational institution in which the student is enrolled; level of education; and expiration date until March 31st of the year following its issuance.
Under no circumstances will bank slips or proof of monthly payments be accepted. See a sample at the link: www.documentodoestudante.com.br

Over 60 years old – Federal Law 10.741/03 and Federal Decree 8.537/15
What to bring: Official photo ID.

Low-income youth aged 15 to 29 – Federal Law 12.933/13 and Federal Decree 8.537/15
What to bring: Youth Identity Card issued by the National Youth Secretariat, accompanied by an official photo ID.

Person with disability – Federal Law 12.933/13 and Federal Decree 8.537/15
What to bring: Benefit Card for Continuous Social Assistance for People with Disabilities or a document issued by the National Social Security Institute – INSS that certifies retirement in accordance with the criteria established in Complementary Law No. 142, of May 8, 2013. At the time of presentation, these documents must be accompanied by an official photo ID.

Teachers from the state public school system and principals, pedagogical coordinators, supervisors, and holders of support staff positions in state and municipal schools. – State Law No. 14.729/12 and State Law No. 15.298/14
What to bring: Employee ID card issued by the Municipal Department of Education of São Paulo or pay stub accompanied by an official photo ID.

Retirees from the city of São Paulo – Municipal Law nº 12,325/1997
What to bring: Official photo ID and INSS (Brazilian National Social Security Institute) benefit card proving eligibility.