### January 23, 2017

**Sabrina Ouazzani**(LACL)

In this talk, we present infinite time Turing machines (ITTM), from

the original definition of the model to some new infinite time

algorithms.

We will present algorithmic techniques that allow to highlight some

properties of the ITTM-computable ordinals. In particular, we will

study gaps in ordinal computation times, that is to say, ordinal times

at which no infinite time program halts.