Show Reference: "A General Method in Proofs of Undecidability"

A General Method in Proofs of Undecidability In Undecidable Theories (1953) by Alfred Tarski edited by Alfred Tarski, Andrzej Mostowski, Raphael M. Robinson
    address = {Amsterdam},
    author = {Tarski, Alfred},
    booktitle = {Undecidable Theories},
    chapter = {1},
    editor = {Tarski, Alfred and Mostowski, Andrzej and Robinson, Raphael M.},
    keywords = {decidability, logics, math},
    posted-at = {2014-01-08 11:25:37},
    priority = {2},
    publisher = {North-Holland Publishing Co.},
    title = {A General Method in Proofs of Undecidability},
    year = {1953}

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A model is a substitution of variables in a theory by objects (individuals) which satisfies all the theory's sentences.