 In intuitionism, knowing that a statement A is true means having a proof of it. In 1934 Arend Heyting, who had been a student of Brouwer, introduced a form of what became later known as the Brouwer-Heyting-Kolmogorov-interpretation, which captures the meaning of the logical symbols in intuitionism, and in constructivism in general as well. It defines in an informal way what an intuitionistic proof should consist of by indicating how the connectives and quantifiers should be interpreted. 