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  \frametitle{Timeline: From Logic to Computability}

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    \alert{1900} & Hilbert's 23 Problems in mathematics
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    \colemph{1921} & Sch\"{o}nfinkel: Combinatory logic
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    \alert{1928} & Hilbert/Ackermann: formulate 
      completeness/decision problems 
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      & for the predicate calculus
        (the latter called `Entscheidungsproblem')
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    \colemph{1929} & Presburger: completeness/decidability of theory of addition on $\mathbb{Z}$  
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    \alert{1930} & G\"{o}del: completeness theorem of predicate calculus
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    \alert{1931} & G\"{o}del: incompleteness theorems for first-order arithmetic
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    \colemph{1932} & Church: $\lambda$\nobreakdash-calculus 
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    \colemph{1933/34} & Herbrand/G\"{o}del: general recursive functions
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    \alert{1936} & Church/Kleene: $\lambda$\nobreakdash-definable $\;\sim\;$
                                 general recursive
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    & Church Thesis: `effectively calculable' be defined as either     
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    & Church shows: the `Entscheidungsproblem' is unsolvable  
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    \alert{1937} & Post: machine model; Church's thesis as `working hypothesis'
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    & Turing: convincing analysis of a `human computer'
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    & leading to the `Turing machine'
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