An Etymological Dictionary of Astronomy and Astrophysics
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فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory

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Number of Results: 9 Search : tree
binary tree
  درخت ِ درین   
deraxt-e dorin

Fr.: arbre binaire   

In → graph theory, an → ordered tree with all → nodes having at most two → children.

binary; → tree.

factor tree
  درخت ِ کروند   
deraxt-e karvand

Fr.: arbre des facteurs   

A diagram representing a systematic way of determining all the prime factors of a number.

factor; → tree.

hartree
  هارتری   
hartree

Fr.: hartree   

A unit of energy used in atomic and molecular physics; symbol Ha or Eh. It is defined as: 1 Ha = mee4/(4ε02ħ), where me is the mass of electron, e its charge, ε0 the → permittivity of vacuum, and ħ → reduced Planck's constant. Its value is 2 → rydbergs, or 4.3597 x 10-18 → joule, or 27.213 → electron-volts.

Named for the British physicist and mathematician Douglas R. Hartree (1897-1958).

merger tree
  درخت ِ تشک   
deraxt-e tašk

Fr.: arbre de coalescence   

A method used in → numerical simulations for studying the growth and development of galaxies and → dark matter halos. Within the currently accepted ΛCDM cosmology, dark matter halos merge from small → clumps to ever larger structures. This merging history can be traced in simulations and stored in the form of merger trees. Merger trees are necessary because a galaxy may have more than one → progenitor at an early time.

merger; → tree.

ordered tree
  درخت ِ بارایه   
deraxt-e bârâyé

Fr.: arbre ordonné   

In → graph theory, a → tree in which the → children of each → vertex are ordered.

ordered; → tree.

rooted tree
  درخت ِ ریشه‌دار   
deraxt-e rišedâr

Fr.: arbre raciné   

In → graph theory, a → tree in which one → vertex is distinguished from the other vertices and is called the root.

root; → tree.

tree
  درخت   
deraxt (#)

Fr.: arbre   

1) A tall, woody perennial plant usually with a single trunk.
2) Math.: → factor tree.
3) A → data structure that is used to represent hierarchical data.
4) In → graph theory, a → connected graph with no → cycles.
5) A mathematical structure that can be viewed as either a graph or as a data structure. Many powerful algorithms in computer science and software engineering are tree based algorithms.

M.E., from O.E. treo, treow "tree, wood," from P.Gmc. *trewan (cf. O.S. trio, O.N. tre, Goth. triu), from PIE *deru- "wood" (cf. Mod.Pers. dâr "tree;" O.Pers. dāruv- "wood;" Av. dāuru- "piece of wood, tree trunk;" Skt. dāru- "tree, wood;" Gk. drus "tree;" Serb. drvo "tree;" L. larix "larch tree;" Rus. drevo "tree, wood;" Pol. drwa "wood;" Lith. derva "pine wood;" O.Ir. daur, Welsh derwen "oak").

Deraxt "tree;" Mid.Pers. draxt "tree," two possible etymologies. A suffixed variant of dâr "tree," cognate with E. tree, as above. Alternatively, from Av. *draxta- "firmly stood, fixed" (as in handraxta-), from drang-, dranj- "to fix, fasten, strengthen, hold," dražaite "holds," infinitive drājnhe; cf. Khotanese drys- "to hold;" Sogdian drγ- "to hold;" Parthian Mid.Pers. drxs "to endure."

tree structure
  ساختار ِ درختی   
sâxtâr-e deraxti

Fr.: structure en arborescence   

A type of → data structure in which each element is attached to one or more elements in a hierarchical manner. Trees are often called inverted trees because they are normally drawn with the root at the top.

tree; → structure.

tree view
  دید ِ درختی   
did-e deraxti

Fr.: arborescence   

A graphical representation that displays a hierarchical view of data.

tree; → view.