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Terminal: run. Derivation Graphs: (left-to-right) compact / full; (top-down) full / compact.

Help: blue = parse inside. Abbr.: WS: Workspace; Initial WS: initial heads for Merge after LEX lookup.

WS n, n = 1,2,... for intermediate stages after Initial WS. Final WS: when WS items converge on a single SO.
Bracketing: {...} (Merge). {...} (FormSet). At Spellout, {...} indicates free word order. [word] indicates word is optionally present.
Head Hd_{selection/features}, e.g. p_θ = predicate head p that seeks a θ-relevant (θR) IA from the WS. p_θ is a θ-seeker (θS).
v_see:θ:pst = head v has complement see, a θR EA from the WS and TNS. v is also a θS.
INFL seeks θR from its complement (not the WS).
Complementizer C comes in different flavors wrt. Force, .e.g. declarative C, interrogative C_Q and relative clause head C_rel.
Features, e.g. TNS pres/pst or DET the/a (shorthand for a bundle of semantic features).
Note: φ-features, e.g. 1sg, appear only at Spellout. Some words do not project, turn into features, e.g. determiners.

Words: who did Mary like

Initial WS 1: like_θ v_like:_θ:_pst:_ext(do) Mary INFL_v who

WS 1: {like_θ, Mary} v_like:_θ:_pst:_ext(do) INFL_v who

WS 2: {v_like:_θ:_pst:_ext(do), {like_θ, Mary}} INFL_v who

WS 3: {who, {v_like:_θ:_pst:_ext(do), {like_θ, Mary}}} INFL_v

WS 4: {INFL_v, {who, {v_like:_θ:_pst:_ext(do), {like_θ, Mary}}}}

Final WS: {C_Q:_{aux(null,pst,like):}_left(who), {INFL_v, {who, {v_like:_θ:_pst:_ext(do), {like_θ, Mary}}}}}

INT/EXT: {C_Q:_{aux(null,pst,like):}_left(who), {INFL_v, {who, {v_like:_θ:_pst:_ext(do), {like_θ, Mary}}}}}

EXT: who null pst like →→ 3sg pst like Mary

Spellout: who 3sg pst do like Mary

Spellout: who did like Mary

Blocked: inconsistent with input!

WS 1: {like_θ, Mary} v_like:_θ:_pst:_ext(do) INFL_v who

WS 2: {v_like:_θ:_pst:_ext(do), {like_θ, Mary}} INFL_v who [gray]

WS 3: {Mary, {v_like:_θ:_pst:_ext(do), {like_θ, Mary}}} INFL_v who

WS 4: {INFL_v, {Mary, {v_like:_θ:_pst:_ext(do), {like_θ, Mary}}}} who

WS 1: {like_θ, who} v_like:_θ:_pst:_ext(do) Mary INFL_v

WS 2: {v_like:_θ:_pst:_ext(do):_box(who), {like_θ, who}} Mary INFL_v

WS 3: {Mary, {v_like:_θ:_pst:_ext(do):_box(who), {like_θ, who}}} INFL_v

WS 4: {INFL_v, {Mary, {v_like:_θ:_pst:_ext(do):_box(who), {like_θ, who}}}}

Final WS: {C_Q:_{aux(null,pst,like):}_left(who), {INFL_v, {Mary, {v_like:_θ:_pst:_ext(do):_box(who), {like_θ, who}}}}}

INT/EXT: {C_Q:_{aux(null,pst,like):}_left(who), {INFL_v, {Mary, {v_like:_θ:_pst:_ext(do):_box(who), {like_θ, who}}}}}

EXT: who null pst like →→ Mary 3sg pst like

Spellout: who 3sg pst do Mary like

Spellout: who did Mary like

Parse found: who null pst like →→ Mary 3sg pst like

WS 1: {like_θ, who} v_like:_θ:_pst:_ext(do) Mary INFL_v

WS 2: {v_like:_θ:_pst:_ext(do):_box(who), {like_θ, who}} Mary INFL_v [gray]

WS 3: {who, {v_like:_θ:_pst:_ext(do):_box(who), {like_θ, who}}} Mary INFL_v

WS 4: {INFL_v, {who, {v_like:_θ:_pst:_ext(do):_box(who), {like_θ, who}}}} Mary

WS 1: {Mary, who} like_θ v_like:_θ:_pst:_ext(do) INFL_v

WS 2: {like_θ, {Mary, who}} v_like:_θ:_pst:_ext(do) INFL_v

WS 3: {v_like:_θ:_pst:_ext(do):_box(who), {like_θ, {Mary, who}}} INFL_v

WS 4: {{Mary, who}, {v_like:_θ:_pst:_ext(do):_box(who), {like_θ, {Mary, who}}}} INFL_v

WS 5: {INFL_v, {{Mary, who}, {v_like:_θ:_pst:_ext(do):_box(who), {like_θ, {Mary, who}}}}}

Final WS: {C_Q:_{aux(null,pst,like):}_left(who), {INFL_v, {{Mary, who}, {v_like:_θ:_pst:_ext(do):_box(who), {like_θ, {Mary, who}}}}}}

INT/EXT: {C_Q:_{aux(null,pst,like):}_left(who), {INFL_v, {{Mary, who}, {v_like:_θ:_pst:_ext(do):_box(who), {like_θ, {Mary, who}}}}}}

EXT: who null pst like →→ {Mary,[and],[]} 3sg pst like {Mary,[and],[]}

Spellout: who 3sg pst do {Mary,[and],[]} like {Mary,[and],[]}

Blocked: EXT inconsistent!

Blocked: inconsistent with input!

Initial WS 2: like_θ v_like:_θ:_pst:_ext(do) Mary INFL_v C_rel:_who

WS 1: {like_θ, Mary} v_like:_θ:_pst:_ext(do) INFL_v C_rel:_who

WS 2: {v_like:_θ:_pst:_ext(do), {like_θ, Mary}} INFL_v C_rel:_who

WS 3: {Mary, {v_like:_θ:_pst:_ext(do), {like_θ, Mary}}} INFL_v C_rel:_who

WS 4: {INFL_v, {Mary, {v_like:_θ:_pst:_ext(do), {like_θ, Mary}}}} C_rel:_who