29 Jan. 2010, Keun Hyun Oh

Self-replication from random parts30 Mar. 2010, Keunhyun OhSaul Griffith, Dan Goldwater, and Joseph M. JacobsonMIT Media Lab0Nature, vol. 437, pp. 636, 2005.Soft Computing Lab.Dept. Computer ScienceYonsei Univ. Korea0ContentsOverview

Related worksKey feature of biological replicationPrevious studies

Proposed methods

Experiments

Summary and future works1/15The autonomous self-replicationAutonomously self-replication machinesnot yet to acquire the sophistication of biological systems, which assemble structures from disordered building blocks

The autonomous replication of complex systems from random inputsA replication of a reconfigurable string of partsRandomly positioned input componentsComponentsSuitable Miniaturized and mass-producedConstituting self-fabricating systems whose assembly is brought about by the parts themselves

2/153/15Key feature of biological replicationSelecting the appropriate building blocks(nucleotides) from parts (ex. DNA)Partsrandomly and continuously distributed in its environment

Correcting errors made during copying

The efficiencyEnabling biological systems to generate exponential numbers of accurate copies of themselves as a function of time

To create these propertiesAutonomous acquisition of randomly distributed building blocksCarrying out error correction during the copying process4/15Previous studiesA scheme for the autonomous self-replicationA simple 2-bit mechanical string outlined almost half a century ago

Using structured inputs has since been achieved

Including a self-reproducing machine that relies on a well-ordered supply of its building blocks

5/15The complexity of a given structureThe bit length describing the configuration of parts in this case, a 5-bit string

the error per addition(arising from random input) of each new building block in the copied string

(1- )nThe yield for replicating an n-bit stringExponentially small for complex (large n) systems ( = 0.5, n=5; the yield is about 3% in the case described here)

6/15Error correctionFor complex structures to be copied accurately from random inputs

A process in which a linear increase in resource leads to an exponential decrease in error rate

DNA replicationthe polymerase enzymes responsible for copying may also check each recruited nucleotide base for correct complementary base-pairing with the DNA template strandif the incoming base does not fit, it is removed by the enzymes exonuclease domain.

7/15To implement error-correcting replicationA set of programmable electromechanical componentsRun as a 7-state, finite-state machinethe components can be reversibly latched and unlatched in response to nearest neighbor communicationsThese parts interact by floating on a two-dimensional air table on which motion is random

Self-replication of this sequenceA result of a random part latching on to the seed stringthe part is queried for self-similarity and proper position in the growing replicantsubsequently it is either permanently latched or released according to an embedded rule

8/15Growing MachinesS. Griffith, 2004

9/156-state machineS. Griffith, 2004

10/15Electromechanical units

11/15An example of latching each other

12/15Self-replication of a 5-bit stringFigure 1 shows a series of frame shots that start with a single-seed string (coloured in a green, green, yellow, yellow, green sequence).

13/15ResultThe kinetics of these processes are exponential until they become limited by the supply of parts(Fig. 2).

14/15Another formation

15/15Summary and future worksSummaryThe autonomous replication of complex systems the ability of the DNA template to select the right building blocks A set of randomly scattered partsThe ability to correct copying errorsdeveloping machines for the autonomous self-replication of a reconfigurable string of parts from randomly positioned components.

Future worksMachines will be more miniaturized Possible to create a general systemself-replicating and programmed to self-fabricate into complex structures that run with exponential kinetics.Thank you16